Week 3 - External flow simulation over an Ahmed body.

Aim :

To run the external flow simulation over an Ahmed Body and to plot the velocity and pressure contours and analyse.

Ahmed Body :

Ahmed Body is a practical Standard model which was developed by Ahmed forresearch purpose ,used to validate the Simulation results using experimental setup.

Significance :

• Simulation results can been verified by the experimental model created.
• Simulation results could be improved based on the actual results.

Geometry :

The geometry of Ahmed body is shown. The file given is importede in ANSYS Space claim.

and an enclosure is made over the Ahmed body to setup the wind tunnel. The results are also plotted with an small enclosure to make the geometry more refined.

Space claim model of Ahmed Body :

Meshing :

Sectional view of baseline mesh Multizone meshing method.

The outer enclosure is refined to 0.1 m element size and the inner enclosure is refined by 0.05 m element size.

Named selections are given in the Mesher.

Physics Setup :

The Model has been solved by the density based solver due to the compressibility of the fluid. Air is chosen as a medium to run the simulation.

The Inlet velocity is set to 25 m/s and the default air material properties is taken into account.

A steady state simulation is performed with 500 Iterations and the Velocity and Pressure contours are plotted.

Two different Independent Mesh Studies has been carried out

Default Mesh Size :

Nodes : 16654

Elements : 84443

Refined Mesh :

Nodes : 40499

Elements : 142136

Thus Mesh Independent Study has been Performed and the Lift and Drag Plot are computed and shown.