Numerical simulation of the Ahmed vehicle model near-wake

FRANCK G.; NIGRO N.; STORTI M.; D'ELÍA, J.

LATIN AMERICAN APPLIED RESEARCH

UNS

Lugar: Bahía Blanca; Año: 2009 vol. 39 p. 295 - 306

0327-0793

The unsteady flow around the Ahmed vehicle model is numerically  solved for a Reynolds number of 4.25 million based on the model  length. A viscous and incompressible fluid of Newtonian type governed by  the Navier-Stokes equations is assumed.  A Large Eddy Simulation (LES) technique is applied together  with the Smagorinsky model as Subgrid Scale Modeling (SGM) and a slightly modified van Driest near-wall damping. A monolithic computational code based on the finite element method is used, with linear basis functions for both pressure  and velocity fields, stabilized by means of the  Streamline Upwind Petrov-Galerkin (SUPG) scheme combined with  the Pressure Stabilizing Petrov-Galerkin (PSPG) one.   Parallel computing on a Beowulf cluster with a domain decomposition  technique for solving the algebraic system is used. The flow analysis is focused on the near-wake region, where the  coherent macro structures are estimated through the second  invariant of the velocity gradient (or Q-criterion) applied on  the time-average flow.  It is verified that the topological features of the time-average  flow are independent of the averaging time and grid-size.