FloTHERM Basic Training
Jay Chien易富迪科技 / EFD Corporation http://www.efd.com.tw
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 1 INTRODUCTION TO FloTHERM
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Lecture Agenda
3
• What is CFD?• What does FloTHERM do?• How does FloTHERM work?• Creating a FloTHERM model• Starting FloTHERM• Application windows• Creating and editing geometry• Help
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
What Is CFD?
4
“Computational Fluid Dynamics or CFD is the analysis of systems involving fluid flow, heat transfer and associated phenomena, such as chemical reactions by means of computer-based simulation”
Versteeg & Malalasekera, “An Introduction to Computational Fluid Dynamics: The Finite Volume Method”
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM – What Does it do?
5
• Solves airflow and heat transfer problems in electronics equipment
• Airflow is the movement of air caused by natural (buoyancy) or mechanical (fans) forces
• Heat transfer is the transfer of thermal energy because of a temperature difference
• Three modes exist…
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Conduction – which is the transfer of heat through a solid or stationary fluid
Convection – which involves the transfer of heat from a surface to a moving fluid
Radiation – which involves the transfer of heat between two or more surfaces
FloTHERM – What Does it do?
6
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM – What Does it do?
7
1. Conduction through a solid or a stationary fluid
Heat Flow
T1 T2
T1 > T2 Q = kA(ΔT/Δx)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM – What Does it do?
8
2. Convection from a surface to a moving fluid
Moving Fluid T2
Surface T1
Heat Flow
T1 > T2Q = hAΔT
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM – What Does it do?
9
3. Radiation heat exchange between two surfaces
Surface T1
Surface T2
T1 > T2
Q = εσA(Thot4 -Tcold
4)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM – What Does it do?
10
• FloTHERM divides both the solid and fluid spaces into many small grid cells and solves conservation equations within each cell.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
How Does FloTHERM Work?
11
• Airflow and heat transfer are governed by the following equations:• Conservation of Mass (continuity)• Conservation of Momentum• Conservation of Energy
• These equations are known as the Navier-Stokes Equations
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
How Does FloTHERM Work?
12
• The Navier-Stokes Equations can be expressed in a common form
• Partial differential equations, therefore can not be solved in “raw” form
SgradVdivt
transient + convection – diffusion = Source
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
How Does FloTHERM Work?
13
• Need to use the Finite Volume Approach• Taylor series expansions• Equations are non-linear and coupled, therefore, the solution
is obtained by iteration
PltltlzlzhzhzlylyhyhylxlxhxhxPP Saaaaaaaa P
hz
lt
lx
hx
hy
ly
lz
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Types of FloTHERM Models
14
Package Level Board Level
Rack
Level
Environment
Level
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
The Procedure for Modeling in FloTHERM
15
Project Manager
LibraryFloMCAD.BridgeDrawing Board
Solver
FloVIZ
Command Center
Pre-Process
CFD Solver
Post-Process
Optimization
Web PartsFloEDA.Bridge
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model
16
• Start FloTHERM• E.g. for windows…
• Start/Programs/MentorMA/FloTHERM 11.3/FloTHERM 11.3 or
• Click on the icon
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Project Manager and Drawing Board window)
17
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Project Manager window)
18
The Project Manager is the first window that shows up when FloTHERM is launched. In this window you can access all settings applied to your model, including: Geometry Material and Thermal properties Solver and modeling settings User preferences
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
19
The Drawing Board allows you to view and manipulate your geometry, as well as add new geometry via the Geometry Palette that we will see later in this presentation.
Creating a FloTHERM Model (Drawing Board window)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Visual Editor/Tables Window)
20
Tables or Visual Editor-Click on either icon to launch
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Profiles Window)
21
Profiles window-Click on icon to launch
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (FloMCADBridge window)
22
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (FloEDABridge window)
23
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Creating Geometry)
• Geometry can be added using the Geometry Palette located in both the Project Manager and the Drawing Board
24
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Editing the Model)
25
• After adding geometry to your model, you will have to define its properties and what it does.
• This is done by adding Attributes– For example:
– What it is made of (material)– How much heat it gives out (thermal)
– There are two ways to do this;– Define your own attributes– Select one from FloTHERM’s preloaded Library
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Editing the Model)
26
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Mouse Operations
Switching mouse modes accomplished by:1. Clicking the various icons in the toolbar2. Using to toggle between Manipulate mode and
SelectF9
27
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Keyboard Shortcuts
X
X
Y
Y
Z
Z
[SHIFT]
[SHIFT]
[SHIFT]
View from Positive X-Axis
View from Negative X-Axis
View from Positive Y-Axis
View from Negative Y-Axis
View from Positive Z-Axis
View from Negative Z-Axis
L
V
Level with Gravity
View selected object(s)
R Refit view
F12
F12
Hide Selection
Reveal Selection[SHIFT]
28
I[SHIFT] Isometric View
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Align
29
Select “Fix” object first and then select “Move” object.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model (Getting Help)
30
Help Resources…— On-line Help
– Available via the Help button in all FloTHERM windows
— Support– Launches the Mentor Graphics support site,
Supportnet.— Report a Problem On-line
– Brings you directly to a window to submit a Service Request.
— Submit Enhancement Request– Brings you to the Mentor Graphics IDEAS
site.— Mechanical Analysis Community
– Brings you to the Mechanical Analysis window of the Mentor Graphics Communities.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 2 BASIC BUILDING BLOCKS AND
INTRODUCTION TO SMARTPARTS
31
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating a FloTHERM Model
32
• Some Definitions:• Primitive - Fundamental geometric entities in FloTHERM• SmartPart - Object parametrically created out of Primitives• Assembly - A group of Primitives, SmartParts and Sub-Assemblies• Attribute - A property that can be attached to Primitives and
SmartParts (e.g. Material)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• The amount of “the world” to include in model is given by the Solution Domain.
• Must include all geometric and thermal / flow features needed to define the model
• Defined using position and size• Right-click on the System Node to access the dialog
Defining the Environment (Solution Domain)
33
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Defining the Environment (Global System Settings)
34
• The reference values within the Solution Domain are set in the Global System Settings:• Right-click on the System
Node in the Project Manager tree
• Select Global
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Solution Domain size – Rules of thumb for forced convection
For forced convection models (e.g. with fans)— Make the domain the same size as
the external chassis— Heat transfer in this model is
dominated by forced convection— Heat loss by natural convection is
minimal from the walls— Heat loss by radiation is also minimal
(no radiation calculations required)
35
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Solution Domain size – Rules of thumb for Natural convection For naturally convected models (no fans
present)— Make the domain bigger than the
chassis— For the space above the chassis,
allow for 2xheight of chassis.— For space below chassis, allow for
1xheight of chassis— Around the sides of the chassis, allow
for 0.5x to 1x width and depth of chassis
— We will also need to turn on Radiation
— Up to 50% of heat transfer is by radiation, the other 50% by natural convection
x
y
Min 0.5x
y
2y
z0.5z
36
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• Certain objects in the Geometry Palette are considered Primitives, and certain objects are considered SmartParts
• SmartParts always have a “Construction” dialog. They are considered smart because they can handle more complex geometries• The Enclosure SmartPart allows you to cut holes into the sides• The Perforated Plate SmartPart allows you to define the venting pattern
• Cuboids and Sources are two examples of Primitives
What Makes a SmartPart Smart?
37
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Cuboid (Primitive)
38
• Cuboids are the basic building blocks of your FloTHERM model:• A cuboid is used to represent any solid
object in the space (Walls, equipment etc.)• Two modes
• Collapsed (2D) or Non-collapsed (3D)• Modes can be toggled without re-entering
data
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• Sources are used to define thermal boundary conditions in your FloTHERM model:• A source can be located in either solid or
fluid• Available thermal boundary conditions
include• Fixed heat dissipation• Fixed temperature• Linear heat dissipation W.R.T.
temperature• Heat per unit volume• Heat per unit area• Transient heat dissipation
Source (Primitive)
39
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• To model a hollow box, use the Enclosure SmartPart
• The enclosure SmartPart consists of a hollow cuboid shaped box with six solid walls, each of which can be: • Optionally removed• Treated as thick or thin• Holed by one or more resistances or other materials
Enclosure (SmartPart)
40
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Perforated Plate (SmartPart)
41
• Use the Perforated Plate SmartPart to define vents in your enclosure
• The Perforated Plate performs an automatic calculation of flow resistance based on construction data that you enter:
• Hole size• Hole arrangement • Hole pitch• Free area ratio
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Organizing the Model(Project Manager Tree Hierarchy)
42
• The Project Manager tree is processed from top to bottom
• If objects overlap:• Objects lower in tree take precedence• Exception – Sources always add
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• Monitor Points are usually located in critical areas in regards to temperature or air flow
• They allow us to track the solution efficiently, and to quickly determine if our solution is indeed steady state
Keeping Track of the Solution (Monitor Points)
43
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Keeping Track of the Solution (Monitor Points)
44
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Recommended - Monitor Point Convergence
- IF the temperature monitor points do not vary by more than 0.5 deg C during 30 iterations
AND - IF the Temperature residual is lower than 10
THEN stop the solution
Monitor Point convergence can be used to avoid excessive solution times for those instances where the Termination Residual is too strict.
45
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Tutorial 1-1
46
Solution domain : 200x200x200 mmMB : 200x1.6x200 mm
FR4 CPU : 25x5x25 mm
Typical QFN15W
Heatsink base : 60x60x5 mmFin number : 15
Fin Height : 25 mmFin Width : 1.2 mmAL 6061
Axial Fan : YSTechYW06025012BS
Ambient : 45 degC
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 3GRIDDING
47
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
48
Grid lines automatically appear along edges of all objects Object associated If the object is Moved Resized
Keypoints do too!
Keypoint Gridlines
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
System Grid Tool
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
System Grid Tool – Maximum Size
50
Max Size = 25 mm Max Size = 75 mm
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
System Grid Tool – Minimum Size
51
Min Size = 0.2 mm Min Size = 2 mm
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
System Grid Tool – Smoothing
52
No Smoothing Smoothing Activated
Abrupt Transition
Large Aspect Ratio
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
System Grid Tool – Gridding Advice
53
Simple models with a few objects approx. same size – use “Coarse, Med., Fine”
Complicated models with many parts (very big and very small objects) – don’t use
Use manual settings (Max and Min cell size)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraints
54
Grid constraints are used to define grid ON geometry
Sets the Minimum Number of Cells, or Maximum Cell Size within the object
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraints - Summary
55
Grid Constraints allow us to specify:— Minimum number of cells across a piece of geometry— Maximum size of cells across a piece of geometry— Minimum size overrules the system grid setting!— Object associated
– Resizing, copying, save/retrieve from the Library Manager
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraints for Objects
56
Minimum # 15 Grid Constraint attachedNo Grid Constraints
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraints - Inflation
57
Controls grid around an object Two key inputs;
— Inflation Distance— Grid cells in inflation distance
Low and High sides independent
Constraint is Max. Size or Min. Number
Inflation distance defined as Size or percentage of object
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraint - Inflation
58
As an example…
– High constraint max. size of 10 mm over 100 mm.
– And the result...
– Low constraint min. of 2 cells for 10% of size
10% of Objects X size
100 mm
High X side
Low X side
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Constraints - Inflation
59
Inflation Distance = 60 mm
Number of cells = 8
Object associated as well Repositioning, resizing, copying and Library saving/retrieving will retain this setting
60 mm
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Using Regions to Define Grid
60
Grid Constraints can be applied to regions Allows grid to be placed in areas where there are no objects
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Using Regions to Define Grid
61
For example, between two plates
2. Define Region3. Attach Grid
Constraint4. Check Grid
1. Define Geometry
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Localized Grid
62
It allows— Reduction in total number of cells— Reduction in maximum aspect ratio (better grid quality)— Allows more grid cells around areas of importance— Stops very small and fine cells “bleeding” out to rest of the
model— Solution time is reduced
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
How to Localize Grid ?
Select object, Assembly or Regiona) Use shortcut in PM or DB, or,b) Check Localize option in
“Location” dialog box
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Localizing grid steps
64
1. Select object, Assembly or Region2. Attach Grid Constraint3. Inflate the Grid Constraint4. Localize grid
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Localize the Grid ! (with inflated grid constraints)
65
Unlocalized Localized
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
BUT what if I don’t inflate the grid ?
66
Unlocalized Localized
• Without grid inflation:• Solid geometry in contact
with edge of localized grid• Grid due to heat sink fins
“bleeding” out
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
What if I have many important objects and I want to localize all of them ?
67
• Use Regions, , as dummy grid objects to place the localized boundary precisely where needed
• Convenient for cluttered geometries that need to be localized
• Graphical indication of the localized boundary is helpful for grid setup
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Localized Grid - Positioning
68
Localized grid spaces can be nested as needed
Can externally or internally abut another localized space
Localized boundary can be completely in solid, fluid, or both.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Cell Aspect Ratios advice
69
Rules to remember:— Aspect Ratio (L1/L2) of grid cells should be as close to unity as
possible.– 1 is ideal– < 20 good
– >200 convergence trouble is likely
— Transitions from large cells to small cells should be avoided
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Avoiding large aspect ratios and small cells
70
Aspect Ratio Problems:— Minimum Cell Size (System Grid)— Build models with a reasonable tolerance (i.e., build objects to the
nearest mm, inch; depends on the scale of the problem)— Avoiding the creation of small grid cells to begin with decreases
chances of Large Aspect Ratios
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Good Grid advice - Heat Sinks
71
Across a channel:
• 3+ cells for an accurate heat transfer prediction
• 5+ cells for an accurate pressure drop prediction
Across a fin:
• 2+ cells in the solid
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Good grid advice – Components and hot objects
72
For components that are capable of predicting junction and case temperatures (2R, Delphi, or Detailed)
• 6 cells in the 1st millimeter above the component
Note: This is automatically taken care of in FloTHERM v8 when using Auto Grid option in FloEDABridge
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Good Grid advice - PCBs
73
For printed circuit boards
• 3 cells in the 1st millimeter above the board
• 3 cells in the 1st millimeter below the board
Note: This is automatically taken care of in FloTHERM v8 when using the Auto Grid option in FloEDABridge
More generally, this rule is applicable to any surface with a significant amount of heat convecting off it
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Steps to get good grid
74
Set up System grid — Max size 10% of total domain size— Min cell size ≤ smallest object in model— Smoothing
Localized and inflated grid around important objects, or Localized and inflated grid around objects which generate a
lot of cells Keep cell aspect ratio < 200
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Simple Example
75
Smoothing
Localized grid
Minimum 2 cells in thickness of solids
Inflated grid – capturing thermal boundary layer
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid Independence
76
Traditional Definition
The point at which the doubling of the number of grid cells causes no change in the solution
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
77
Grid Independence
Engineering Definition
The point at which the addition of a large number of grid cells no longer significantly affects the solution.
Significant = 5%, 3% etc
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Tutorial 1-2
78
• System Grid Tool : Solution domain
• Grid Constraints : MB & CPU
• Region : Localized Grid
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 4 POST-PROCESSING
79
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
View Manipulation – Mouse Operations
Switching mouse modes accomplished by:1. Clicking the various icons in the toolbar2. Using to toggle between Manipulate mode and
Select
3. Using to toggle between all three modes.
F9
ESC
80
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
View Manipulation – Keyboard Shortcuts
X
X
Y
Y
Z
Z
[SHIFT]
[SHIFT]
[SHIFT]
View from Positive X-Axis
View from Negative X-Axis
View from Positive Y-Axis
View from Negative Y-Axis
View from Positive Z-Axis
View from Negative Z-Axis
I
L
V
Isometric View
Level with Gravity
View selected object(s)
R Refit view
F12
F12
Hide Selection
Reveal Selection[SHIFT]
81
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Hiding/Revealing Geometry
Select Geometry— Graphically in Visual
Editor— Project Manager tree— Visual Editor— Tables
F12
F12
Hide Selection
Reveal Selection[SHIFT]
F12[CTRL] Reveal all hidden objects
82
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
View Manipulation – Two Views
Perspective View Orthographic View
83
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Visualizing the Model• Visual Editor window allow views of:
• Results• 3D representation of model
• Model can be represented as:• Solid view• Wireframe view• Switch between views using Mode Palette• Or, use “w” or “s”
wireframe
Solid
Surface Plot
84
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• Use selection Mode to select objects in model
• Use manipulator to rotate, zoom, pan model
• Annotate mode allows annotations to be added to picture
• Keyboard shortcut to above modes:
• “F9” to toggle between• Escape key to toggle
between
Selection Mode
Manipulator Mode
to cursor position
Using the Mouse
85
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Assigning Colors to Geometry In the Visual Editor window, you have the ability to override the default
colors assigned to an object. To do so:
Select the object Click on Material->Color in the
lower left pane of the Visual Editor window
86
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Assigning Textures to Geometry The Visual Editor also allows you to assign an image to
the surface of an object. To do so:
Select the object Select one of the preloaded
image files or attach your own
87
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating 2D scalar plots(Plane of Temperature)
• In the Visual Editor, you create 2D planes showing the temperature distribution anywhere inside of the Solution Domain.
1. Select the Create Plane icon 2. Go to the Property Sheet in
the bottom left corner, ensure that the Scalar checkbox is checked
3. Select Temperature in the drop down menu
1
2 3
88
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating 2D Vector Plots(Plane of Velocity)
• Planes showing Velocity Vectors can be created using the same method as the Temperature plane
• Uncheck the Scalar checkbox• Check the Vector checkbox
• To move the plane to the desired location
• Use left or right cursor keys• OR, use the Manipulator arrow• Make sure that the “Show
Manipulator” option is ticked
89
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Post Processing – Annotations
Annotate Mode
Single click – add Annotation to
1. Geometry
2. Plane Plots
3. Isosurfaces
4. Surface Temperatures
90
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating 2D Contour Line Plots
Set in Contour Plane property sheet— Cell Fill (calculated results for
every single cell – no interpolation)
— Interpolated (results are interpolated to give smooth distribution)
— Contour lines
91
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Grid on Contour Plots
Set in Contour Plane property sheet
If model has no results— Use Solve –
Reinitialize in Project Manager
OR, simply press “g” to toggle the grid on or off
92
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Post Processing – Tables
Icons to switch into Tables Mode
The four modes are:
Geometry Only
Tables Only
Tables On Right
Tables Below
93
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Post Processing – Tables• Table types and options are held
under the Tables node.
• Selecting an object row in the Tables window highlights that object in the Project Manager and graphically in the Visual Editor, and vice versa.
• Data sorting is possible with all column headings.
• Data can be directly pushed into your spreadsheet program.
94
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Particle Streamlines Visual Editor allows you to create particle streamlines showing how a
massless particle would move through your product.
To create a particle source:1. Select an object that
will be used as the particles origin
2. Select the Create Particle Source in the Creation Palette at the top of the window.
2
1
95
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
You also have the ability to view Surface Plots on one or more of the objects in your model.
Surface Plots available include:— Temperature— Computational
Mesh/Grid NOTE: to turn off
the Surface plot, select either the Wireframe or Solid view
Wireframe view, or “w”
Solid view, or “s”
Surface plotSurface Plots
96
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scalar Fields – changing the temperature scaleWill contain items for all Scalar quantities in the Solution set
Each Scalar will have it’s own property sheet
97
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Saving Viewpoints You can save View Points in the Visual Editor window using the Save
Viewpoint icon located in the palette at the top of the Visual Editor window. You can recall these viewpoints at any time by selecting the desired view in
the list of saved viewpoints on the upper left pane of the Visual Editor window
98
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Saving pictures and movies
To save a screenshot,— Use short cut icon (camera)— OR, Viewer/Output Snapshot in the menu— Can be saved as png, bmp or jpg format
To save a animations of the particles,— Use short cut icon,— Note that this will create an animation of
the particle motion only— It will not animate any Viewpoint animation
99
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Creating particle and viewpoint animations
To create a movie of rotating viewpoints and particle motion, — Use the shortcut icon, — OR Viewer/Output Movie— An *.avi file will be created
The compression codec can also be chosen:— Default is No Compression— There are 4 other formats— Recommend Microsoft Video 1 for
compatibility reasons— The created movie will be able to run
on all Windows PCs (without having to download other codecs)
100
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 5 COMMAND CENTER
101
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Lecture Agenda
102
Basics Introduction Inputs Outputs Solving
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Examples of Optimizations
103
Size and placement of fans and vents Layout of components Heat sink fin count and geometry Fan speeds versus desired component temperature
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scenarios
104
Base case model has been created and solved Many engineering questions still exist:
— How to improve thermal performance?— How will design operate in different environments?— Is this design the optimal design?
Command Center allows:— Test model in different scenarios— Optimizing model’s thermal design
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Where to Start
105
Load your base case Click the Command Center icon
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Command Center Application Window
106
1. Input Variables
2. Graphical Input
3. Output Variables
4. Scenario Table
5. Solution Monitoring
.....
5 Different Tabs/Windows
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Input Variables
107
Double-click the parameter to vary:— ‘Use as Input
Variable in Scenario’ toggled on
Define the variation method:— Ad Hoc— Linear— Design Parameter— Linear Function
Scenario/Reset can be used to clear all settings in Command Center
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Input Variables
108
Ad Hoc:— Manually specify all variable values— Use the Append button to add a variation
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Input Variables (Cont.)
109
Linear:— Input Variable varied with a specified increment— Enter the Step Size and Number of Steps to define the variants
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Input Variables (Cont.)
110
Design Parameter:— Sets the range of an Input Variable (Minimum and Maximum
values)— A pre-requisite for the automated design tools: Design of
Experiments, Response Surface Optimization, and Sequential Optimization
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Input Variables (Cont.)
111
Linear Function:— Allows linear relationships (y = ax + b) to be defined between
Design Parameters— For use with Design of Experiments, Response Surface
Optimization, and Sequential Optimization
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Possible Command Center Variations
112
Scalars:— Position— Size— Ambient conditions— Gravity orientation— Thermal resistance— SmartPart parameters
– Heat Sink # of fins, fin widths, fin height– Fan volume flow rate
— Grid settings— Power dissipations— And more
Non-Scalar:— Fan failed analysis— Deactivate/Activate
objects– Different fan
models— Swap Library
Attributes– Material (steel to
aluminum)– Surface finish
(polished to anodized)
– Interface materials— Turbulence model— And more
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Graphical Input
113
List shows all existing scenarios— Initially, only the
base case is visible (# 0)
Switch between scenarios by clicking name
Simplified Drawing Board— All shortcut keys— Most Drawing
Board functionality— New geometry
cannot be created
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Graphical Input (Cont.)
114
Check each of the cases Remember to check the
grid for each case by pressing ‘g’ on the keyboard
......
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Output Variables
115
Define the data of interest required from the scenarios
Saves disk space:— Storing full solution is
possible Not limited to Monitor
Points Define cost function
— Required for Response Surface Optimization and Sequential Optimization
.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scenario Table
116
Input Variables— The value for
each scenario (column) can be modified
Solution settings and current status of each scenario
Output Variables— The values will
update as the scenarios solve
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scenario Table (Cont.)
117
Right-click the settings in the white area to make a change Store Results:
— None— Full— History Only
Initialize From:— All from Base Project— All from No Project— All from Previous Project
Typically use the base case results as the initialized point— Minimize use of disk space
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scenario Table (Cont.)
118
Ready to solve? Hit GO!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Scenario Table (Cont.)
119
• After pressing GO, the Solution Status for each project displays;– Solved– Solving– Queuing
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Solution Monitoring
120
• View the Profiles graphs for each simulation
• Viewable while a solve is active
• Convergence is still important!
....
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Results – Scenario Table
121
If the full set of data is required, a scenario can be saved as an individual project;— Load into Project
Manager— Required to view results
in Visual Editor Right-click on the scenario
title (top row of the column) and choose Save As
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Tutorial 1-3
122
• Heatsink Base• Fin Number• Fin Width
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 6 USING MCAD DATA
123
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Agenda
Introduction Simplification Data Conversion Voxelization Additional Functions
124
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Importing CAD files using FloMCAD Bridge
Process: Read in ACIS (.sat), STEP (.stp or .step), IGES (.igs) or STL (.stl)
neutral data format files (parts and assemblies) Alternatively, read in ProE, Solidworks or CATIA files (parts and
assemblies) Simplify MCAD geometry Convert MCAD geometry into FloTHERM entities
Data can also be transferred from FloTHERM to FloMCAD Bridge
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Data Import FloMCAD Bridge uses the ACIS solid modelling kernel Incoming data has to be converted to ACIS format This conversion is done by ‘Translator (read) Husks’
FloMCAD.BridgeACIS (SAT)
STEP
IGES
SAT
ProE
FloTHERM
STL
Catia
Solidworks
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
1. Simplification
What is the benifit of a thermal simplification?— The reduction of the geometry to an efficient AND accurate
thermal model What constitutes a thermal simplification?
— The removal of thermally insignificant geometry e.g.– Small holes– Small humps– Small chamfers and fillets
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Simplification – Where to do it
In your favourite MCAD tool (ProE, Solidworks, CATIA etc) before you export the data— Suppress or delete thermally irrelevant feature like branding logos,
drilling holes, small filets, small chamfers etc.— Suppress irrelevant parts like screws etc.
In FloMCAD using Global and Local Simplification, Replace Tool, Decompose
In FloTHERM after the model was processed in FloMCAD and transferred
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Global Simplification
Easy way to quickly perform therm simplifications Works on selected MCAD part or body From [Tools / Global Simplify] or Right click on selected object, then pick [Global Simplify]
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Global Simplification – Check the result
Seeing what has just been simplified— Sometimes it is not exactly clear how the geometry has been
simplified— Use CTRL-Z for toggling between ‘before‘ and ‘after‘ simplification
CTRL-Z
CTRL-Z
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Local Simplification
Total control over what is simplified to what extent Targets specific areas for simplification Manually intensive! [Tools / Local Simplify] or Right Click on selected object, pick [Local Simplify] from pop
up menu Hot Keys may be used:
+ Add bounding box- Subtract bound
DEL Removef Flattenl Level
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Local Simplification – Example
Feature Simplification— A feature is a collection of faces constituting a geometric pattern— Feature are derived by FloMCAD from the topology of neighbouring
faces— Features can be removed upon selection
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Simplification – The Golden Rule
The golden rule of thermal Simplification:
Simplify at least to the extent where the geometry could be created manually in
FloTHERM!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
2. Data Conversion
Simple geometry or parts for which a SmartPart exists:[Tools / Single Object]— Replaces a single Part/Body with a FloTHERM Primitive/SmartPart— FloTHERM Primitives: Cuboids, Prisms and Flow Resistances— FloTHERM SmartParts: Fan, PCB, Enclosure, Cylinder and
Perforated Plate Other simple geometry:
[Tools/Decompose]— Automatically simplifies the CAD geometry— Automatically dissectects the CAD geometry— Automatically replaces dissected geometry with ‘Single Objects‘
Dissect already simplified geometry Any other geometry: Voxelize it!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
[Tools / Single Object]— Select the MCAD part or body to convert— Pick the [Tools / Single Object] menu or click on the icon the left
tray or right click on the selected object and pick [Single Object] from the pop up menu
— Select the most apropriate FloTHERM entity
Single Objects
FloTHERM Fan SmartPart ready to be transferred to the Project Manager
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Single Object Example
Simplifying Grille Work: Arrays of holes or slots can be removed by selecting two oppsing faces then replace with a Perforated Plate
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Single Object Remarks
When an MCAD part is replaced with a FloTHERM SmartPart, default parameters are used.
Each SmartPart can be considered as ‘placeholder‘ Each SmartPart has to be reviewed after the transfer to
FloTHERM! Examples:
— Fan: Adjust Hub Diameter, Flow Specifications, Swirl etc.!Hint: In FloTHERM, replace the Fan SmartPart with a fan from the libraries
— PCB: FR4 and Cu are attached; Adjust Cu content!— Perforated Plate: Adjust hole pattern and hole size!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Dissection
Dissection is the process of converting the selected MCAD object into a collection of FloTHERM primitives— The MCAD object is automatically and successively split in to
smaller MCAD bodies— These smaller bodies are constantly analyzed to check whether
they can be replaced with single objects (cuboids, prisms, sloping blocks or cylinders) or further automatic splitting is required
— User can control resolution, butleave the first three setting atdefault (no need to modify if thegeometry was simplified sufficiently)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Dissection – Curved Faces
Arc/Chord Ration is used to determine how an MCAD body with a curved face is split into smaller bodies— The closer A/C is to 1.000 the
better the curve will be resolved
— If the default is too coarse try 1.05 or 1.01
— The closer A/C is to 1.000 the more FloTHERM entities will be used
A
C
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Decompose
Decompose automatically simplifies and dissects a geometry [Tools / Decompose]
— Select the MCAD part or body to convert. If none is selected the entire geometry will be decomposed (often unwanted).
— Pick the [Tools / Decompose] menu or right click on the selected object and pick [Decompose] from the pop up menu.
— Set an apropriate Simplification Level and Apply. Start with ‘Simple‘ levels.
— Use [Edit / Undo] or CTRL-Z to move back and forth, repeat previous step until right level of simplification is achieved.
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Decompose Example
Example: Shield
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
3. Voxelization – When nothing else works ...
Voxelization is a process that converts MCAD geometry to a collection of (small) cuboids
Use it when the CAD geometry is too complex and [Tool / Single Object], [Tools / Decompose] or Dissect cannot be used
FloMCAD Bridge
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization – always a good idea!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization - General
Creates a stair stepped representation of the geometry User controls how many cuboids are created Extremely robust
— Always resulting in a FloTHERM representation— Especially when compared to the ‘Dissect‘ process
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization - Inputs
Use [Tools / Voxelize] or click with a part or body selected
Choose either ‘Minimum Number‘ or ‘Maximum Cell Size‘ and enter apropriate values for X,Y and Z directions
An apropriate setting for the Minimum Cell Size will ensure no extremly small cuboids will be created
Collapse Thickness sets thethickness of all collapsed cuboidscreated during the process(when combining 2D faces)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization – How it works
Overlay grid is specified— Having the bounding box
keypointed— Then having each vertex
keypointed— Then adding additional lines to
satisfy either a minimum number or a maximum size constraint
— If two grid lines are closer together than the minimum cell size one of the lines is removed
For each cell inside the original geometry a cuboid is created
Each cuboid pair that share a full face will be merged into one, repeatedly
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization – Modeling advices
Set the minimum cell size to the smallest dimension that requires representation
Try different values of Minimum Number or Maximum Size until the desired level of resolution is achieved (use CTRL-Z to toggle ‘before‘ and ‘after‘)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Voxelization – Modeling Advices
After transfer into FloTHERM, make sure to inflate and localize the grid on the transferred assembly
Use grid constraints that matches the cell size used
Assign a Material Attribute on the assembly instead of assigning it to individual cuboids
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
4. Split Body
Useful when parts/bodies are too complex to be processed in one
Split Body Procedure:— Select MCAD body— [Tools / Split Body] or— Right click, pick ‘Split
Body‘ from pop up menu— Select a Face or Vertex— Slice— Split
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Align with Axes
Set Selection Mode to ‘Face‘ Rotate Align Part:
— Select the planar face of a part you would like to align to the global cartesian coordinate system
— [Tools / Rotate Align Part] Rotate Align Assembly:
— Select the planar face of a part in the assembly you would like to align
— [Tools / Rotate Align Assembly]
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Top & Hide
Parts or bodies can be topped up in the same way as in the Project Manager— Very useful when an assembly containing multiple parts is imported— Parts can be topped up and converted to FloTHERM entities
Parts or bodies can be hidden in the same way as in the Project Manager
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Subtract Bodies
Example: Creating a circular hole— In FloTHERM: Create a plate and a
cylinder, radius = 0.5 x hole diameter
— [External / Import Project Geometry]— Select the object from which we
want to subtract the other— CTRL-Select the body to be
subtracted— [Tools / Subtract]— Process resulting body
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• After geometry is converted to FloTHERM entities, use [Tools/Transfer Assembly] FloTHERM
• FloMCADBridge and FloTHERM conserves the part name
153
5. Data Transfer to FloTHERM
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Transferred MCAD model in FloTHERM
Remember, transferred parts and assemblies:— Do not have any material properties— Do not have any thermal properties— Do not have any radiation properties
Some parts and assemblies will also need grid constraints Transferred MCAD model will have the same positions as in
original CAD model Part names will also be transferred
154
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Tutorial 2
155
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 7USING EDA DATA
156
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Lecture Agenda
Introduction to FloEDABridge
EDA Direct interfaces Processing Components
— Filtering, Component Swapping, Power, Viewing Library Manager Processing the PCB
— Layers, Vias, Stackup Other Capabilities
— Heat sinks, Thermal vias, EM cans, Potting, Daughter boards Transferring to FloTHERM Post Processing Continued
157
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloEDABridge
FloEDABridge
intelligently import EDA data into FloTHERM
Use FloEDABridge to create thermal representations of the PCB and IC components for use in FloTHERM
158
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
EDA Direct Interfaces
Interfaces and user manuals provided with the FloTHERM installation. Interfaces are available for:— Boardstation: 2005BST or later— Cadence Allegro: 15.7 or later— Zuken CR5000: v9 or v10— Expedition EE2007.8 or later— Cadence APD
159
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Direct Interfaces – Boardstation
EDA interface files are installed into Boardstation Creates a FloTHERM Interface menu Allows the board information to be extracted into a FloEDA file
160
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Direct Interfaces – Allegro & Expedition
Similar process for Cadence Allegro & Expedition All the Settings options are identical to the Board station interface
161
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Direct Interfaces – CR 5000
Uses 3 ASCII output files created by pcout, mrout, and ftout Zuken utilities— pcf (board data)— mrf (manufacturing data)— ftf (footprint data)
Requires license feature ZX0409 Files then converted to FloEDABridge file using supplied command
line utility— ZukenBrdDesToEDAI –job xyz –out xyz.floeda
162
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloEDABridge Interface
Data Tree
Property Sheet
Library ManagerGraphical View
Viewer Settings Toolbar
Alignment Toolbar
New Geometry Toolbar
Show Library
163
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Viewing the Board Layout Board displayed 2 ways
— Data view— Graphical view
– 2D and 3D
Data view can be shown in 2 different ways— Tree View— Component Table
164
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Component Filtering
Allows filtering of thermally insignificant components Various options
— Side length— Height— Power— Power Density— Reference Designator
Filter results in deactivated component Delete removes component completely
165
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Automatic Component Swapping Tools\Component Library
Swap will replace components with objects saved to the Library.
If package name matches Library name, then package is replaced
— Component will be same location and orientation as original
The user specifies which Library folders should be searched for matches.
166
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Manual Component Swapping
Manual Library Swapping from a right-click pull down
The user specifies which Library item should be swapped in
This applies to most objects you see in FloEDA.Bridge (PCBs, Heat Sinks, stackup, etc.)
167
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Power Maps Apply power
values to multiple components
Simple .csv file— 1st column =
Reference Designator
— 2nd column = Wattage
Can re-import to update
168
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Library Manager Accessed via the Library icon Adding Library components to model
— Select motherboard/daughterboard— Double-click valid Library item
Or— Select component in model— Double-click Library component to “swap”
– Functional groups can also be “swapped”
Or— Select object to receive Library item— Right-click Library item— “load”
Or— Select item in model— Right-click— Replace with Library item …
– Or— Add Library item …
169
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Saving to Library Manager
Use the Library Manager to save items for future models
Select item (motherboard, component, etc)
Right-click “Save To Library …”
— Create new Library folder first by right-clicking (keeps Library organized)
170
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Metallic Layer and Electrical Vias Processing Attach high resolution image of each
metallic layer OR Imported directly with ‘.floeda’ file.
FloEDA file also contains image of through-hole vias. You will need to manually attach this image to the vias in the board tree if a FloEDA files was not utilized.
Images can be processed into a collection of layer patches
— Automatically derived effective thermal conductivities for each patch
Individual resolutions for each layer image
If .floeda file is unavailable— manual attachment of
monochrome image is supported Unprocessed images will have an
orthotropic cuboid created with % Cu calculated from image
171
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Processing Tool
Resolution Slider determines patch size
% Cu bands slider determines the number of orthotropic conductivity material properties created
Click ‘Show’ to see the original image.
Trace layer example, vias processed similarly in same window.
172
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Board Layer Stack up Property window to set placement of trace layers within the depth of the PCB. Option of ‘Equispaced’ which automatically sets the layer spacing.
173
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Guidelines
Conduction cooled applications require high resolution of copper traces— Forced convection in general does not— Warning message appears for more then 500 patches
Power planes, due to their high percentage copper, typically can be left un-processed
Results can be quite dependent on the slider bar settings. Be sure to do a sensitivity analysis when accuracy is paramount
174
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
New Geometry in FloEDA Bridge
We can create:— Heatsinks— Thermal and Electrical vias— Cylindrical components (capacitors)— Components (detailed, compact)— Cutouts— Daughter boards— Additional copper layers— Copper patches— EMC cans— Potting compounds
These can be created either in FloEDA Bridge (easier), or in FloTHERM later.
175
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Transfer to FloTHERM
File – Transfer— Transfers motherboard and all children to FloTHERM— !!! Save in FloEDABridge in case of future design updates !!!
– Transfer is a one-way street– Can’t transfer back from FloTHERM into FloEDABridge
176
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Assembly Structure in FloTHERM
Motherboard is placed as last node in Project Manager tree
Tree Structure— Cutouts— Layers— Vias— Top/Bottom Side
– Potting compound, components, Heat Sinks, vias, daughterboard, can
— Regions – Generated for localizing grid
(created by the Auto Gridding feature)
177
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
FloTHERM Structure - Notes
Simple components represented with Cuboids Heat Sink represented with SmartPart Patches represented with Hole SmartPart, filled with
generated Material Properties Each component has its own Region created
— Useful for gridding and obtaining numerical results
178
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Tutorial 3
179
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 8 RADIATION
180
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Radiation For naturally convected systems,
radiation is important Contributes as much as 50% of
total heat transfer By default, radiation is OFF. To turn it on for the calculations,
go to PM/Model/Modeling 3 options:
— Radiation off (default)— Radiation on— Radiation on – High Accuracy
(additional 2-3% more accurate, but > 3% additional solver time) Not recommended to be used.
181
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
2. Preparing Geometry for radiation exchange
We need to attach Radiation Attributes to surfaces that take part in radiation exchange
Create new attributes— Single radiating surfaces, or,— Sub-divided Radiating surfaces
Attach these surfaces to the external surfaces of the selected part
182
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Single radiating surfaces
Remember, For single radiating surface, there is
only ONE value of Thot or Tcold— FloTHERM will calculate the average
surface temperature for the entire surface. Then use this in the radiation equation.
If surface temperatures are uniform, then this is OK.
But if there is a significant temperature difference, then results will not be accurate
Surface T1
Surface T2
T1 > T2
Q = εσA(Thot4 -Tcold
4)
183
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Sub-divided radiating surfaces
Significant temperature difference on a surface – use subdivided radiating surfaces
The selected surface will be subdivided into N number of segments — Note that these segments are different
from the grid cells ! Average surface temperatures are
calculated for each segment Radiation heat exchange equation
repeated N times
50mm
Q = fεσA(Thot4 -Tcold
4)
184
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Settings to be used
For single radiating – we only need to enter “Minimum Area Considered”— We can use the default value of 0m2
For sub-divided radiating, we need:— Subdivided Surface tolerance— Minimum Area Considered
Subdivided Surface tolerance is the length of each small segment — e.g. If our surface area = 1m (H) x 1m (W)
we use a surf. Tolerance = 50mm. This means that we get 1000/50 x 1000/50 =
400 segments
50mm
1 m
185
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Minimum Area Considered
If we have an object with a large surface area, but is very thin (e.g. a PCB)
Side area is very small Negligible radiation from side Therefore we can use “Minimum area
considered” to tolerance out the sides of the PCB— E.g. if PCB is 500x500x1.6mm— To tolerance out the sides, we enter an
area = 801 mm2
PCB thickness = 1.6mm
500mm
500mm
Side area = 800 mm2
186
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
3. Surface finish (Emissivity)
We need to consider the emissivity (ε) of the radiating surfaces
Value varies from 0-1 — 0 means there is no emissivity or radiation— 1 means it is a blackbody
To define emissivity for Smartparts, we do it through the materials attribute:— we assign “Surface Name”— Emissivity value is specified— NOTE that if Library Manager materials are
used, then a default ε value is given
For primitives like cuboids, prisms etc.— We can also use the Surface Attribute to define
ε,— Or, we can use Material/Surface Name
187
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Radiation Model and limitations
The Gray Body radiation model is used in FloTHERM— This is a better approximation of everyday objects used
Surface to surface radiation considered. Increase in fluid temperature due to radiation will not be considered.
FloTHERM will determine the View Factor or Exchange Factor (efg.exe) automatically
If there are too many radiation surfaces or segments, then the Exchange Factor calculation will take much longer (also use up a lot of RAM)
Efg.exe may crash if you have millions of segments and you run out of RAM !
Each iteration will take much longer to complete
188
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 9 TROUBLESHOOTING
288
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Residual Profiles and definitions
190
R esidualE rror
Ite ration
ResidualError
Iteration
Convergence
Divergence
Stable
ResidualError
Iteration
ResidualError
Iteration
Oscillating
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Why doesn’t my model converge ? (Steady state models)
191
Common reasons: — Errors made during set up— Grid not adequately refined— Inappropriate Termination Criteria— Control Parameters not suitably set— Natural Instability
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
First step - Sanity Check
192
Checks the model for potential errors in the problem setup
Can be run independently of the solver
Avoid wasting time on ill-posed problems!
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Sanity Check (Cont.)
193
• Problems reported in Message Window
• Errors: Model can not be run• Warnings: Something might be wrong with the model• Informationals: Items of interest. Not usually indicative
of a problem
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Sanity Check Example
194
• Warning - Object has been entirely overwritten• Cause: hierarchy rule not followed
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
2nd Step – Check for Model Input Errors
195
Input Errors during set up; — Unrealistic values
– Entering 5 MW instead of 5 mW— Unrealistic geometry
– Eg: Placing a fan so half of it is inside a wall— Problem is ill-posed
– Sealed system with no material for the enclosure
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
3rd step: Check the Grid
196
• There needs to be sufficient grid to capture all of the relevant physics:
• Add grid where you suspect the largest temperature and velocity gradients will be present;
• Heat sources• Heat sinks• Fans• Inlet/Outlets vents
• The Field Error tool is a great way to identify where more grid should be added
Smoothing
Localized grid
Minimum 2 cells in thickness of solids
Min 2 cells in hot solids, Min 3 cells in narrow channels
Min 6 cells in 1st mm above hot objects/chips, Min 3 cells in 1st mm above & below PCB
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Error Field Tool
197
Activate Error Field Storage; — Set in Solver Control
Error Field Storage saves the error in each Grid Cell;— Visual Editor to locate
maximum/minimum error— Display the grid
– Error field uncovers poor grid
Error located in unimportant area;— Monitor Points reached steady state
– No need to force convergence
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
4th step: Check Termination Criteria
198
Examples;— System with multiple fluids (i.e. air and water)
– Termination criteria is based on air density — System with ducts and fans
– Termination criteria based on maximum fan velocity
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
5th Step: False Time Steps
199
Set under Solver Control The values for x, y, z velocities and Temperature can be
changed (User Specified) False time steps are used to control the convergence What and how much to change depends on the convergence
graphs
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Converging Profile
200
This is exactly what you want to see in your residual plot
No user action is recommended
R esidualE rror
Iteration
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Diverging Profile
201
— STOP the solution immediately— Check the obvious first
– Examine;– Sanity Check– User Inputs– Modeling Decisions– Grid Inadequacies
— Locate the Problem Spot(s):– Monitor Points and Error Field – Deactivate Objects/Assemblies to isolate problem
— Results will be extremely incorrect — If model and grid are OK, reduce automatic
False Time Step value by 10x first.— Re-initialize before solving a diverging
model
ResidualError
Iteration
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Stable Profile
202
Check user inputs— Common error is neglecting to assign
materials and thus trapping heat– Heat that cannot escape is permanent
residual error!
Check gridding with Field Error Check Termination Criteria
— Try increasing False Time step values (start with x2 automatic value)
If model and grid are OK,— Use Monitor Point plots and
engineering judgment to determine quality of results
— Activate Monitor Point Convergence for Temperature
ResidualError
Iteration
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Oscillating Profile
203
Check Gridding with Field Error Adjust Solution Controls:
— Reduce False Time Step for oscillating variable
— start with 2x reduction of automatic false time steps
Use Monitor Point plots and engineering judgment to determine quality of results
Maybe flow behaviour is naturally unstable (e.g. thermal plume above naturally convected hot object).
May require transient analysis to solve model
ResidualError
Iteration
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Best Practice Techniques
204
Before solving a model:— Sanity Check— Use Monitor Points to track variables at points of interest — Grid carefully with attention to expected areas of large gradients
After solving a model:— System mass flow and energy balance— Error Field to locate maximum error – check the grid
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
LECTURE 10MANAGING PROJECTS
205
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
• Before building, save your project:1. In the Project Manager, click
on: [Project / Save]2. Enter project name3. Choose Solution Directory4. Add Notes
– Allows description to be added to a project
– Could be used to track changes
– Can be displayed from [Project / Load] dialog
Managing Projects (Saving Projects)
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Managing Projects (Loading Projects)
207
• To load an already solved project:1. In the Project Manager click on:
[Project / Load]2. In the upper left window select a
project to load3. Click Load
• If the project of interest is not visible in the upper left window verify that the correct Project Solution Directory is selected.• To select a different Project
Solution Directory select [Browse...] and navigate to an alternative directory
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Managing Projects(Importing and Exporting Projects)
208
Import / Export an entire project via a right-click on the top node in the Project Manager tree
Formats to import:– FloXML– PDML– V1.4 files– V2/V3 *.project– Pack Files
Formats to export:– IGES– PDML– Pack Files– Pack Files (no results)– SAT
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
聯絡我們
209
易富迪科技有限公司
台北市松山區南京東路三段 305 號 5F 電話:+886-2-87724131 傳真:+886-2-27173122 網站:www.efd.com.tw 客服信箱:[email protected]
www.mentor.com© 2013 Mentor Graphics Corp. Company Confidential
Top Related