Thank you Mr.Narale
I have looked up the tutorial and didn't follow it exactly but it went a long way in helping me improve my accuracy, 1. I increased the domain extent so that now i have ablockage ratio of arounf 3% and i have around 4 cars' length behind the car, but i increased the max cell size to keep the cell count down . 2. I changed the model to the one recommended by the course GEKO and changed the CSEP to 1. 3. I used rotating wall bc and didnt use the rotating reference frames for the wheels.
with all of these modifications i improved my Cd percentage error down to a value of only 2.5%, which is acceptable.
You are navigating away from the AIS Discovery experience