Numerical Simulation of Unsteady Flow Around Bluff Bodies

PhD student: Sven Perzon
Supervisor: Lars Davidson
Cooperation: CFD Group, Volvo Cars
Sponsors: Volvo Cars Corp., IVS
Publications: [1,2]
Start of project: February 1999

The CFD group at Volvo has since 1991 been working on external aerodynamics around vehicles. The group has continously been working on developement of the methods to shorten lead times and increase accuracy. Since 1994 the CFD group and the Department of Thermo and Fluid Dynamics have been working together in research projects.
At the CFD group, attempts have recently been undertaken to further increase the accuracy by using finer grid and more advance turbulence models. It was found that with such a fine grid resolution, large turbulent unsteady structures in the shear layers and the wake were resolved by the grid. As a result, no steady solutions could be found.
Volvo aims to replace windtunnel test with CFD. The required accuracy is achievable only with very fine grids, and consequently transient computation must be used. Furthermore, transient computations based on RANS/LES (a combination of Reynols Averaged Navier-Stokes and Large Eddy Simulations) is expected to be more accurate than traditional RANS, as large turbulent structures will be resolved by the grid.
The main object is to develop a CFD method for simulation of external aerodynamic of bluff bodies. The method must be robust with short lead times.
Unsteady numerical simulations will be used, probably a combination of RANS and LES. Suitable bluff-body configurations for the project are:
  • The surface-mounted cube
  • A simplified FH Truck
  • The Volvo ECC (Environmental Concept Car)
  • The Mercedes ASMO

- click to view postscript file
  1. Perzon, S. and Davidson, L..
    On CFD and Transient Flow in Vehicle Aerodyanmics", SAE Technical Paper 2000-01-0873
    View PDF file
  2. Perzon, S. and Davidson, L..
    "On Transient Modeling of the Flow Around Vehicles Using the Reynolds Equation", ACFD 2000, Eds: Wu, J.-H., Zhu, Z-J., Jia, F.-P., Wen, X.-B. and Hu, W., Bejing, Oct. 17-20, 2000.
    View PDF file



This page, Numerical Simulation of Unsteady Flow Around Bluff Bodies, should be part of a frames system at
Ingalena Ljungström
This site uses JavaScript.