Week 3 - External flow simulation over an Ahmed body.

• Ahmed Body: It is a simplified car model which captures the external flow around the model. It is primarily used to validate the CFD results of a virtual model and the results obtained in the wind tunnel of a real model.
• The negative pressure in the wake region is due to the air flowing over and under the model. The air over the body moves smoothly along the slanted region of the top and airflow below the body. due to this, there is a vacuum created behind the body. Due to this, negative pressure is developed behind the body. This is also the primary reason for the Drag coefficient of the body.
• Point of Separation: This is the point where the boundary layer airflow detaches from the surface of the body. This is a cause of pressure-related drag.

Case-1:

Meshing:

Overall mesh quality.

inner bounding box meshing

Inflation layers

Results: Mesh max size:100

Drag Coefficient:0.44

Lift Coefficient:0.49

Contours:

velocity contour

Pressure contour

Vector in the wake region

Results:

Drag Coefficient @ 25 m/s= 0.38

Lift coefficient @ 25m/s= 0.34

Contours:

velocity contour

Pressure contour

Vector in the wake region.