What is CFD??

• Computational Fluid Dynamics is “a

wind tunnel in the computer.”

• It is a method by which one uses certain algorithms or other numerical formulas to analyze the fluids' flow.

• We can say it is the smoke profile made in computer.

APPLICATIONSAPPLICATIONS

Biomedical

Electronics

Defense

Industrial

Environmental

Automobiles

Submarines

Examples of applications of CFDExamples of applications of CFD

Why it is necessary??

To improve product performance & quality.

To Reduce development costs.

To Reduce lead-times and “time-to-market”

To get optimal results.

CFD software is portable, easy to use.

We can modify the geometry if not satisfied

with the results.

Simulations are parallel and multiple-purpose.

Various CFD softwaresVarious CFD softwares

FLUENT

EasyCFD_G

Parallel FEM

ANSYS CFX

FLOW-3D

Passage

NUMECA

CFDesign

FlowEFD

CFD-RC

Phoenics

OpenFOAM

STATCD

Flagship CFD

Aerodynamic Efficiency

Aerodynamicists measure three variables-

downforce drag balance

How does it works?

The analysis begins with building the computer simulated model of a physical problem.

Conservation of matter, momentum, and energy must be satisfied throughout the region of interest.

Fluid and model properties are defined. Simplifying assumptions are made in order to make the problem tractable (e.g.,

steady-state, incompressible, two-dimensional). Initial and boundary conditions are provided. The computer software divide geometric structure into specific cells or grids. The set of algebraic equations are solved numerically to calculate the quantities on

each of the cell. The resulting data is used to compute the quantities of interest (like- mass,

momentum, pressure, lift, drag etc.) and effects of all of these on the model

unstructured computational mesh (5 million cells)

Computer simulated model of ship

- The higher number of cells, gives more accurate results.

- CFD also concern with the ignition process of gasoline in order to create power.

- It gives Simulations of hot exhaust gases, engine cooling, brake heating/cooling events, tire deformations, and fuel filling and sloshing.

How does it works?

Meshing

Domain is discretized into a finite set of control volumes or cells. This process is called as meshing.

The meshing is classified in two main groups-

Unstructured meshing Structured meshing

meshing The structured meshing is again then classified into following sub-types-

triangle

quadrilateral

tetrahedron pyramid

prism or wedgehexahedron arbitrary polyhedron

For simple geometries, quadrilateral or hexahedron meshes can provide high-quality solutions with fewer cells.

For complex geometries, quadrilateral or hexahedron meshes show no numerical advantage, and you can save meshing effort by using a triangular or tetrahedron meshes.

Compute the solution

The discretized conservation equations are solved iteratively. Anumber of iterations are usually required to reach a convergedsolution.

Convergence is reached when: Changes in solution variables from one iteration to the next are

negligible. Residuals provide a mechanism to help monitor this trend.

Overall property conservation is achieved. The accuracy of a converged solution is dependent upon:

Appropriateness and accuracy of the physical models.Grid resolution and independence.

Problem setup.

Supercomputers

BMW Sauber F1 Team- Albert series.

Renault F1 team- Mistral

Force India Formula One Team- eka

Products by CRAY supercomputers.

Post-processingPost-processing

Results are usually reviewed in one of two ways. Graphically or Alpha-numerically.

Graphically:

– Vector plots.

– Contours.

– Iso-surfaces.

– Flow lines.

– Animation.

• Alpha-numerics:

– Integral values.

– Drag, lift, torque calculations.

– Averages, standard deviations.

– Minima, maxima.

– Compare with experimental data.

Contours of static pressure

Bob tailing 

CFD Process

Advantages

It improves the aerodynamic efficiency and capability of racecar.

It enhance the understanding of how various designs will perform.

The more experiments are done in shorter amount f time.

It is capable of analyzing overtaking conditions.

Gives Better fuel economy & limit CO2 emissions.

Overtaking conditions..

Limitations

The millions of calculations are required to be done to get the result.

It is very complex.

It's not 100% effective.

Conclusion

In this way, we can conclude that the Use of CFD is very essential in the design of racecar.

It has many advantages and it also saves time and money.

It reduces human efforts with improved efficiency.

References

Supercomputing in F1 – Unlocking the Power of CFD (2005) http://www.ansys.com/industries/automotive/TPL10715.pdf

Motor Sport Drives CFD Technology to a New Level(2008) http://www.fluent.com/solutions/sports/tn272.pdf

Computational Fluid Dynamics in Formula 1 Design (1999) http://usuarios.multimania.es/motorformula1/Dinamica_de_Fluidos_en_Formula_1.pdf

How Does CFD Work? (5th may 2009) http://www.autoevolution.com/news/how-does-cfd-computational-fluid-dynamics-work-6400.html))