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TECHNICAL PAPERS

Numerical Study of the Flow Around a Bus-Shaped Body

[+] Author and Article Information
Siniša Krajnović, Lars Davidson

Department of Thermo and Fluid Dynamics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden

J. Fluids Eng 125(3), 500-509 (Jun 09, 2003) (10 pages) doi:10.1115/1.1567305 History: Received April 09, 2002; Revised October 30, 2002; Online June 09, 2003
Copyright © 2003 by ASME
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References

Hucho, W-H., 1998, Aerodynamics of Road Vehicles, 4th Ed., Society of Automotive Engineers, Warrendale, PA.
Bearman, P. W., Davis, J. P., and Harvey, J. K., 1983, “Measurement of the Structure of Road Vehicle Wakes,” International Journal of Vehicle Design (Technological Advances in Vehicle Design Series, SP3, Impact of Aerodynamics on Vehicle Design), pp. 493–499.
Ahmed, S. R., Ramm, G., and Faltin, G., 1984, “Some Salient Features of the Time Averaged Ground Vehicle Wake,” SAE Paper No. 840300.
Barlow, J., Guterres, R., Ranzenbach, R., and Williams, J., 1999, “Wake Structures of Rectangular Bodies With Radiused Edges Near a Plane Surface,” SAE Paper No. 1999-01-0648.
Duell, E. G., and George, A. R., 1999, “Experimental Study of a Ground Vehicle Body Unsteady Near Wake,” SAE Paper No. 1999-01-0812.
Ahmed,  S. R., 1981, “Wake Structures of Typical Automobile Shapes,” ASME J. Fluids Eng., 103, pp. 162–169.
Bearman, P. W., De Beer, D., Hamidy, E., and Harvey, J. K., 1989, “The Effect of a Moving Floor on Wind-Tunnel Simulation of Road Vehicles,” SAE Paper No. 880245.
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Duell, E. G., 1994, “Experimental Investigation of Unsteady Near Wakes of Ground Vehicle Bodies,” Ph.D. thesis, Cornell University, Ithaca, NY.
Barlow, J. B., Guterres, R., and Ranzenbach, R., 1999, “Rectangular Bodies With Radiused Edges in Ground Effect,” AIAA Paper No. 99-3153.
Bearman,  P. W., 1997, “Near Wake Flows Behind Two- and Three-Dimensional Bluff Bodies,” J. Wind. Eng. Ind. Aerodyn., 69–71, pp. 33–54.
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Aoki, K., Ohbayashi, T., Zhu, M., and Miyata, H., 1993, “Finite-Volume Simulation of 3D Vortical Flow-Fields About Road Vehicles With Various After-Body Configuration,” SAE Paper No. 931896.
Sohankar,  A., Davidson,  L., and Norberg,  C., 2000, “Large Eddy Simulation of Flow Past a Square Cylinder: Comparison of Different Subgrid Scale Models,” ASME J. Fluids Eng., 122(1), pp. 39–47.
Sohankar,  A., Davidson,  L., and Norberg,  C., 2000, erratum, ASME J. Fluids Eng., 122(3), p. 643.
Krajnović,  S., and Davidson,  L., 2002, “Large Eddy Simulation of the Flow Around a Bluff Body,” AIAA J., 40(5), pp. 927–936.
Ghosal,  S., 1999, “Mathematical and Physical Constraint on Large-Eddy Simulations of Turbulence,” AIAA J., 37(2), pp. 425–433.
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Nilsson, H., and Davidson, L., 1998, “CALC-PVM: A Parallel SIMPLEC Multiblock Solver for Turbulent Flow in Complex Domains.” Internal Report 98/12, Department of Thermo and Fluid Dynamics, Chalmers University of Technology, Gothenburg.
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Figures

Grahic Jump Location
The instantaneous streamlines projected onto symmetry plane z=0 of the bus and the isosurface of the instantaneous pressure, p=−0.20. Note that only half of the pressure surface (for z≤0) is shown.
Grahic Jump Location
Time-averaged velocity profiles at three downstream locations at z=0. Fine grid (solid curve); medium grid (dashed curve); coarse grid (dashed-dotted curve); experiment (symbols).
Grahic Jump Location
Time-averaged streamlines projected onto planes: (a) x=−3.36H, (b) x=−2.88H, (c) x=−1.68H, (d) x=−0.48H, (e) x=0, and (f ) x=0.32H. The direction of the rotation of this vortex (T) is counterclockwise. View from behind of the lower-right edge of the body.
Grahic Jump Location
Time-averaged velocity vectors in plane x=−1.68H. View from behind of the lower-right edge of the bus.
Grahic Jump Location
Instantaneous streamlines at x=−0.48H. The time difference between two pictures is tU/H=3.2. View from behind of the lower-right edge of the bus.
Grahic Jump Location
Time-averaged streamlines projected onto symmetry plane z=0 of the bus. (a) Fine grid, (b) medium grid, (c) coarse grid.
Grahic Jump Location
The isosurface of time-averaged pressure p=−0.20. The black curves represent the vortex cores of the thin edge vortices B, the ring vortex W, and the longitudinal vortices behind the separation bubble P. Vortices on the right side (z<0),P and T, are visualized using streamlines in planes x=1.4H and x=−0.48H, respectively (note that the mirror image vortices on the left side, i.e., z>0, are not shown in this figure). View of the rear face of the body.
Grahic Jump Location
The time-averaged longitudinal vortex in the far wake in plane x=3.52H. View of the rear face of the bus.
Grahic Jump Location
Instantaneous coherent structures in the far wake visualized with isosurface of pressure p=−0.035.Bs is the free stagnation point at the closure of the separation bubble. View of the rear face of the bus.
Grahic Jump Location
Schematic representation of the time-averaged wake flow.
Grahic Jump Location
Time-averaged streamlines projected onto plane x=−0.8H. The rotation of Up and Us is counterclockwise and clockwise, respectively. View from behind of the upper-right edge of the body.
Grahic Jump Location
Geometry of the vehicle body and computational domain
Grahic Jump Location
The topology of the fine grid. Note that only O grid and few blocks around it are shown. One-fourth of the O grid is removed in this figure.
Grahic Jump Location
The isosurface of the instantaneous second invariant of the velocity gradient, 35, Q=11000
Grahic Jump Location
Time-averaged trace lines on the surface of the body showing the roof vortex, R, the lateral vortex, L, and the stagnation point, Sf. View of the front face of the body.

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