[ludvigum]

Hello!

I am conducting a control volume analysis of a car simulation, but for some reason the forces don't add up.

My process: I have set up a force report with all the car parts (from regions) and set the vector direction in the drag direction. I set up a similar force report with just walls, ground, inlet and outlet boundaries from regions as well. Same was done for downforce, just in the downforce direction.

My problem: The drag force and downforce should equal the force reports of the domain in the same directions, but this is not the case. I get an error of approximately 10% for drag and 2% for downforce.

Does anyone have a clue why? I'm thinking it might be the mesh near the wall, but with some refined mesh I still don't get much lower errors.

This is for my master's thesis so it's important that the CV analysis is good for me to be able to trust the results.