A study of vortical structures past the lower portion of the Ahmed car model

Vortical structures that develop past the lower portion of the Ahmed car model (in the φ{symbol} = 25o slant-angle configuration) have been studied numerically. Numerical simulations are executed (at ReL = 2.88 × 106) by means of a finite-volume computational code following the LES approach, and the results are compared with the experimental data obtained by other authors at the same value of the Reynolds number. For further investigation of the flow fields, the method of the imaginary part of the complex eigenvalue pair of the velocity-gradient tensor (λci or swirlingstrength criterion) is applied to the velocity field to extract the turbulence vortical structures. As a result we found that vortical structures of arch type generate from the lower portion of the body, in particular the plane-channel-type zone that is included between the floor of the computational domain and the external side of the body bottom characterized by alternatively high and low turbulent kinetic-energy contents.