What is CFD?
u An Engineering ToolØ Computer “experiments”Ø DesignØ Troubleshooting
u A Numerical MethodØ Solves equations of motion for fluidØ A Graphical User Interface
• set up problem• solve• view results
Computational Fluid Dynamics
CFD: A Numerical Methodu CFD Solves the Navier Stokes
Equations
Getting at the Solution:Interfaceu Problem set up or “Pre-Processing”
Ø integration with design groupØ easy to use interfaceØ parametric studies
u Solver computes the flow fieldØ speed, accuracy, reliability, ease of useØ features “models”
u Viewing Results “Post-Processing”Ø numbers, graphs, figures, animations
The CFD Process
u Create or import your geometry using CAD-style tools
u Discretize the geometry: mesh generation
u Define flow conditions, fluid properties,physics
u Submit the calculation (solution of theconservation equations for mass,momentum, energy, chemical species)
u Review results (graphically, numerically)
What Can be Modeled?
u Screw Compressorsu Centrifugal Compressorsu Expansion Turbinesu Dryersu Separatorsu Filtersu Ductingu Heat Exchangers
u Performanceu Bearing loadsu Clearance effectsu Visualizationu Erosionu Fouling/pluggingu Heat transferu Noise
ResultsDevices
Setting Expectations
u Values forØ PerformanceØ Heat TransferØ ForcesØ Erosion
u Trendsu Parametric studiesu Visualizationu Investment that pays off
u Replacement for goodengineering judgement
u Complete replacement fortesting
u Something for nothingØ Accurate results require
• Detailed models• Knowledge of your problem• Knowledge of limitations
What Not To ExpectWhat To Expect
CFD: The Advantages
u Complements physical modelling.
u Provides comprehensive data not easily obtainablefrom experimental tests.
u Is more cost-effective than physical modelling.
u Reduces the product-to-market time scale.
u Answers the “what if…?” question.
u Highlights the cause not just the effect.
Benefits of CFD
Minimize System Cost
Improve Performance
UnderstandProblems
Reduce Design Time & Expense
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