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