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Measurements in Fluid Mechanics058:180 (ME:5180)Time & Location: 2:30P - 3:20P MWF 3315 SCOffice Hours: 4:00P 5:00P MWF 223B-5 HL

Instructor: Lichuan Guilichuan-gui@uiowa.eduPhone: 319-384-0594 (Lab), 319-400-5985 (Cell) http://lcgui.netwww.lcgui.net (download lectures from this website)

2Lectures - around 40 lectures in class room followed by discussions if necessary- lecture note available on web after each class (http://icon.uiowa.edu & http://lcgui.net )Homework- homework problems assigned MWF, due FMW- Paper version accepted in class, PDF/DOC files accepted by e-mail- late submission with legitimate reason, explained in writingClass project - write computer program with Matlab (sample programs provided)- process digital particle image (PIV) recordings with algorithms introduced in class- start at the beginning of PIV lectures (Matlab program practice & examples earlier) - details may be discussed in the class or office hours- presentation in class when the class lectures are completed- report include introduction, method description, program structure, source code, and results. Examinations- two in-semester 50-minute and one final 120-minute examinations- closed notes and books- one-page formula sheet allowed.3GradingThe final course grade will be based on the total points earned during the semester. The distribution of points is as follows:Homework problems25%= 25Class project25%= 25Two in-semester exams12.5% each= 25Final examination25%= 25TOTAL= 100 points4Text bookMeasurement in Fluid Mechanics, Stavros Tavoularis, 2005, Cambridge, 2005Reference booksParticle Image Velocimetry, Raffelet. al., 2ndEdition, 2007, SpringerParticle Image Velocimetry, Adrian and Westerweel, 2011, CambridgeFlow Visualization, Wolfgang Merzkirch, 2nd Edition, 1987, Academic

5Lecture 1. Fluid properties and continuum hypothesis6Measurements in Fluid Mechanics Mechanics- the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment.Fluid- fluids are composed of molecules that collide with one another and solid objects.- fluids include liquids and gases- fluids are easily deformation materials and take the shape of any container LiquidsGases- relatively high density and difficult to change volume- relatively low density and easily to change volume- tend to occupy the entire available volume of their containerContinuum hypothesis- the continuum assumption considers fluids to be continuous.- fluid property values continuously distributed within volume of fluid- local values defined at an infinitely small fluid element i.e. a mathematical point7Measurements in Fluid Mechanics Measurement- the process or the result of determining the ratio of a physical quantity, such as a length or a mass, to a unit of measurement, such as the meter or the kilogram.Measurements in Fluid Mechanics- Methods and techniques used in the process or for result analysis of determining force, motion and other physical quantities of fluidsFluid mechanics- the study of fluids and the forces on them- fluid mechanics can be divided intofluid statics - the study of fluids at restfluid kinematics - the study of fluids in motion;fluid dynamics - the study of the effect of forces on fluid motionexperimental fluid dynamics (EFD)computational fluid dynamics (CFD)8Measurements in Fluid Mechanics International System of Units (SI)

9Measurements in Fluid Mechanics International System of Units (SI)

10Measurements in Fluid Mechanics International System of Units (SI)

11Measurable fluid properties Mass- quantity of material ( m )SI unit: kilogram (kg), gram (g)Volume- quantity of space ( V )SI unit: cubic meter (m3), liter (=0.001 m3)Density- mass per unit volume ( )SI unit: kg/m3Specific volume - volume divided by mass (v)SI unit: m3/kgForce- any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape ( F )SI unit: newton (N)Body force Surface force - e.g. gravity and electromagnetic forces- acts throughout the volume- acts across an internal or external surface element - decomposed in to two perpendicular componentsNormal component (Fn) Tangential or shear component (Fs)

FFs

A

- force per unit area () SI unit: pascal (Pa=1N/m2)

Shear stressn=Fn/As=Fs/A1112Measurable fluid properties Stress tensor

Normal stresses: 11 , 22 , 33Shear stress: 12 , 13 , 21 , 23 , 31 , 32(12 = 21 , 13 = 31 , 23 = 32)External forces: F1 , F2 ,, FnPressure- force per unit area applied in a direction perpendicular to the surface- average normal stress along any three orthogonal directionsSI unit: pascal (Pa=1N/m2), bar (=105Pa)- Symbol: PViscosity- resistance to deformation because of shear stress (, )Surface tension - property of the surface of a liquid that allows it to resist an external force. SI unit: N/mIndex of refraction - a measure of the speed of light in substance

13Measurable fluid properties Temperature- quantitatively expresses the common notions of hot and cold ( T )SI unit: kelvin (K) WorkEnergy- the ability a physical system has to do work on other physical systems ( E )SI units: joule [J]- the amount of energy transferred by a force acting through a distance in the direction of the force. ( W )SI units: joule [J]Power- the rate at which work is performed or energy is converted. ( P )SI units: watt [W]Heat- an energy transfer to the body in any other way than due to work performed on the body ( Q )SI units: joule [J]Thermal conductivity- material's ability to conduct heat ()SI unit: W/(mK)14Specific heat capacity under constant pressure ( CP )Specific heat capacity under constant volume ( CV )Heat capacity Measurable fluid properties - measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount. ( C )SI unit: J/K

SI unit: J/(kgK)SI unit: J/(kgK)Internal energy - total energy contained by a thermodynamic system ( U )SI unit: JEnthalpy (H)H=U+pVEntropy ( S )dS=Q/THeat flux- the rate of heat energy transfer through a given surfaceSI unit: W/m2- thermodynamic property that can be used to determine energy available for useful work in thermodynamic process- total energy of a thermodynamic system15

Position- Cartesian coordinate system (x, y, z)- Cylindrical coordinate system (, , z)

- Spherical coordinate system (r, , )

P=xi+yj+zkP=cosi+sinj+zkP=rsincosi+rsinrsinj+rcoskMeasurable fluid properties 16P=xi+yj+zkDisplacement- shortest distance from the initial to the final position of a point (x, y, z)

xyzVelocityV=P/t=x/ti+y/tj+z/tk- the rate and direction of change in the position of an object Acceleration- rate of change of velocity over time

a=V/t=[V(t+t)-V(t)]/tMeasurable fluid properties

17Volume flow rateMass flow rate

AVn Measurable fluid properties Vorticity- tendency for elements of the fluid to "spin."Strain rate- rate of change in strain with respect to time ( )

v - speed of deformation

- length under applied stress- original length

18

Angular position( ) Angular displacement ( )

Measurable fluid properties Angular velocity ( )=d/dtAngular acceleration ( ) =d/dt=d2/dt2Momentum- product of the mass and velocity of an object (P=mv).SI unit: kgm/s or NsAngular momentumL=rP= rmvSI unit: Nms or kgm2s1SI unit: radianTorque ( )=rFSI unit: Nm

19HomeworkQuestions and Problems: 1 and 2 on page 17 1. Provide definitions for the following measureable flow properties: angular momentum, entropy, thermal conductivity, molecular diffusivity, and surface tension. 2. List the established names for the SI units of force, pressure, energy, and power and their relationships to primary units. Also list the conversion factors of these units to corresponding units in the British gravitational system.- Read textbook 1.1-1.2 on page 3-5 - Send MS Word or PDF file to lichuan-gui@uiowa.edu - Due on Friday, 08/2419