Hello every body,

for my final year thesis I designed a car body which I now have to analyse in terms of aerodynamic aspects.

To not neglect the "ground effect" I put my vehilce on a flat plate plate 4m x 6m x 1mm.

My computational domain does not include the whole street but "cuts" trough it and goes a few mm below the bottom of the plate.

I also added "real wall"boundary conditions to the plate making it move the opposite direction of the vehicle travel direction.

I wonder now if the plate is part of the lift and drag analysis of the car or not, I obviously want the road to be excluded!

I made a few simple experiments with a cylinder and a plate, but still can't seem to figure out if the plate is part of it or not:

just the cylinder

lift: 21.6

drag: -573 (direction of travel is +)

plate and cylinder

lift: -35 (downforce)

drag: -1393

plate in motion and cylinder

lift: -29

drag: -1364

HELP is very welcome!

Thanks already!

Have a great Sunday!