Recent Advances in External Aerodynamics Simulation of a Hatchback Production Car

Sandeep N Shetty; Vivek patil

doi:10.4271/2013-01-2906

In the present scenario wherein the cost of fuel is ever increasing, maximizing fuel efficiency of a vehicle is one of the prime areas of focus for all the OEM's. Aerodynamic drag forms a prominent portion of the resistive forces acting on a moving car. In the early design phase, engineers are interested to get insight into the flow field around the vehicle so as to take informed design decisions. It would be difficult to build different designs and physically test them. Thus it becomes necessary for all the OEM's to use simulation to predict resistive forces and also to develop a robust simulation procedure which would help them to predict with confidence.

Reynolds Averaged Navier Stokes Equation (RANS) method is used to simulate external Aerodynamics, which is a steady state simulation methodology. The use of Large Eddy Simulation (LES) to model transient simulation is not feasible for production purpose because of huge mesh especially near the walls. Hence Detached Eddy Simulation (DES), which is a combination of RANS and LES modeling approach, can address the time feasibility and accuracy for this kind of unsteady simulation.

In this paper we will discuss the correct meshing guidelines, Steady v/s Transient simulation, best practice for solver setup with respect to accuracy. It will also focus on advanced solving techniques, solver comparisons and mesh conversion, so as to reduce the total time taken for simulation. All results of the simulation are validated with wind tunnel data.

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Recent Advances in External Aerodynamics Simulation of a Hatchback Production Car 2013-01-2906

SAE MOBILUS