Hi all, I am currently completing my dissertation in the field of CFD, using SolidWorks flow simulation. I am aiming to analyse the flow around the Ahmed body and how the addition of a rear diffuser alters both the drag and lift forces as well as the flow at the rear-most section.

I Have constructed a hollow box in SolidWorks and placed the Ahmed body within the box. I have set boundary conditions as follows;

- Inlet velocity on left wall of 40ms^-1

- Outlet "environmental pressure" on right side

- Real wall set to both the right hand side and left side

- Ideal wall set to the floor of the box.

In these boundary conditions, I have used the default turbulence parameters and then set a global initial mesh of 7. Also, I have used a local initial mesh around the body itself and then inserted the goal to find the force in the x direction (Drag). Doing this, the average value in the goals window is 306N, which seems excessively high. To my knowledge, this would refer to a drag coefficient value of around 2.8 which I know is incorrect. I feel there may be an error with my procedure. If there is any confusion about how I have done this, I have linked a very similar method, whose calculations also found a drag value of around 600N .(https://warwick.ac.uk/fac/sci/eng/staff/pd2/es174_car_aerodynamics_manual_2015.pdf )

I would hugely appreciate some support with this, no matter how big or small.

Ryan.