Week 3 - External flow simulation over an Ahmed body.

Conclusion

1. Frontal part of body flow velocity if affected and gets stuck at the front area of body, the remaining fluid flows through the upper and lower surface of body, reaching the rear area of the body. Rear area a detachment of fluid layer takes place creating a separation layer in the wake region. This separation of layer occurs due adverse pressure gradient at the rear end. Slant at the end of body provides direction to the fluid creating a downward force reducing the separation region, and mitigating wake and eventually turbulence.
2. From pressure contour plots the pressure at the front face of Ahmed body is more, increasing the pressure at the front area due to stagnation velocity, as the fluid flows through the fillets of body, the pressure is eventually decreasing, leading to drag force acting on the body.
3. Negative pressure is occurring due to sudden changes is shape of body abruptly, the flow has viscous resistance from the surface and also it has to overcome the adverse pressure gradient, resulting in separation of fluid layer from surface.
4. Since pressure at front part is more than the rear part of Ahmed body, drag force is created, which eventually increases the fuel consumption of vehicle. Therefore reducing of this separation region can be obtained by changing the shape of body at the front and as well as at back.

Sno	Refinement	Coefficient of drag	Lift coefficient
1.	353123 cells	1.2	0.1
2.	440384	1.4	0.25
3.	632384	1.6	0.22