Flow over Ahmed Body

Objective- To understand the air flow over an Ahmed body and calculate the drag and lift coefficients and validate the velocity profile with the experimental data.

CAD-Geometry, Meshing and Solver setup:

Fig(a)- Wind tunnel and Ahmed body Boundary conditions

Flow Conditions:

Fluid Medium- Air

Inlet Velocity[u]=25m/sec

Outlet pressure(absolute)-1 bar

Flow type-Steady

Cases Summary:

Case-1- `phi`=25⁰ with K-Epsilon Turbulence Model

Case-2- `phi`=35⁰ with K-Epsilon Turbulence Model

Case-3- `phi`=25⁰ with K-OmegaSST Turbulence Model

Case-4- `phi`=35⁰ with K-OmegaSST Turbulence Model

where `phi` is the Ahmed body slant angle

Fig(b)- Ahmed Body Dimensions

Fig(c)- Wind Tunnel Dimensions

Fig(d)- CAD Geometry

Fig(e)- Meshers used

Fig(f)- Mesh size Controls for the Wind Tunnel

Fig(g)- Mesh size Controls for the Control volume around Ahmed body

Fig(h)- Cross sectional view of the mesh

Results/Discussion

Fig(i)- Physics Models used

Fig(j)- Velocity Contour for 25 degree slant angle (K-Epsilon)

Fig(k)- Velocity Contour for 25 degree slant angle (K-Omega)

Fig(l)- Velocity Contour for 35 degree slant angle (K-Epsilon)

Fig(m)- Velocity Contour for 35 degree slant angle (K-Omega)

Fig(n)-Drag and lift coefficient values for different cases

Fig(o)-Plane Averaged Velocity at different planes

The drag coefficient increases with the increase in Ahmed body slant angle.