Numerical simulation of the Ahmed vehicle model near-wake

Gerardo Franck, Norberto M. Nigro, Mario Alberto Storti, Jorge D'Elia


The near-wake structure of the flow around the Ahmed vehicle model
is numerically achieved by a time-averaged procedure of the unsteady
flow modeled by the Navier-Stokes equations with a Large Eddy
Simulation (LES) model for the turbulence . The Reynolds (based on
the model length) and the Mach numbers are fixed in 4.25 million and
0.18, respectively. A viscous and incompressible fluid model of
Newtonian type is assumed. A LES technique together with the
Smagorinsky model as Subgrid Scale Modeling (SGM) and the van
Driest near-wall damping is employed. The coherent macro structures in
the near-wake are estimated through the second invariant of the
velocity gradient (Q-criterion) applied on the time-average
flow. A monolithic computational code is employed, which is based on
the finite element method with equal order basis functions (linear)
for pressure and velocity and uses a Streamline Upwind Petrov-Galerkin
(SUPG) scheme combined with a Pressure Stabilizing
Petrov-Galerkin(PSPG) one. Parallel computing on a Beowulf
cluster with a domain decomposition technique for solving the
algebraic system is used. [Submitted to Int J Num Meth Fluids]

Full Text: