C. Chok et al., NUMERICAL INVESTIGATION OF THE EFFECTS OF BASE SLANT ON THE WAKE PATTERN AND DRAG OF 3-DIMENSIONAL BLUFF-BODIES WITH A REAR BLUNT END, Journal of wind engineering and industrial aerodynamics, 51(3), 1994, pp. 269-285
A computational model has been developed to help the automotive design
engineer to optimize the body shape with minimum wind tunnel testing.
Unsteady, Reynolds-averaged, Navier-Stokes equations have been solved
numerically by a finite-volume method and have been applied to study
the flow around Ahmed's vehicle-like body. The standard k-epsilon mode
l has been employed to model the turbulence in the flow. The finite vo
lume equations have been formulated in a strong conservative form on a
three-dimensional, unstructured grid system. The resulting equations
have been solved then by an implicit, time marching pressure-correctio
n based algorithm. The steady state solution has been obtained by taki
ng sufficient time steps until the flow field ceases to change with ti
me within a prescribed tolerance. For the pressure-correction equation
, a preconditioned conjugate gradient method has been employed to obta
in the solution. Most of the essential features of the flow field arou
nd a bluff body in ground proximity, such as the formation of trailing
vortices and the reverse flow region resulting from separation, could
be well predicted. In addition, the variation of the drag coefficient
with the back slant angle agreed reasonably well with the experimenta
lly observed values.