### Numerical simulation of the Ahmed vehicle model near-wake

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

#### Abstract

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]

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]

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