Car Aerodynamics

OpenFOAM® methodology of external aerodynamics of the car including flow in the engine compartment parts, fan and heat exchangers

A typical project we often have in our company is switching from commercial software to the OpenFOAM®. At the beginning there was a request from our customer to develop complete methodology and Best-Practice setup for CFD simulations of external aerodynamics including the engine compartment using OpenFOAM® on computational meshes supplied by the customer - mesh was prepared in a commercial software.

The main task was to calculate and evaluate the aerodynamic coefficients (drag Cd and lift Cl) and the forces acting on the front and rear axle of the car and analyze the flow in the engine compartment. Another important task was evaluating flow rates on many predefined zones around the car body. Part of the customer’s demand was also a complete training of its engineers. The customer wanted to switch to OpenFOAM® to save the costs associated with the purchase of licenses for commercial software.

It was necessary to model the flow through heat exchangers including the flow through the rotating fans in the engine compartment. The simulation was set up as a steady state incompressible turbulent flow. Cost savings compared to commercial software was not negligible (solution is used daily by four customer’s engineers). Original solver suffered from slow convergence, we adjusted it and found the appropriate setup, which satisfied customer’s demand on the speed and accuracy of the computation. New, stabilized OpenFOAM® solver is more robust and converges faster to steady state. Flows, forces and aerodynamic coefficients are evaluated on the fly and user can monitor their convergence.

OpenFOAM CFD simulation of a car body - pressure magnitude

We have successfully resolved the given task and introduced OpenFOAM® and Best-Practice methodology for calculations of the external aerodynamics of the car with the engine compartment. We achieved results with better than required accuracy. The training of customer’s employees also took place. As a bonus, we also prepared the methodology that solves the entire CFD process of external aerodynamics simulations using only open source technologies.

Please contact us for further information.

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