Lattice Boltzmann, LIFT and DRAG forces
 

Dear community,

I am a newbie of this forum.

I am working on a 2D developed laminar flow (Re 100) in a channel and a square cylinder as an obstacle. Simple stuff

I want to calculate de drag coefficient and the peak-to-peak lift coefficient, so which is the best strategy to calculate it?

I am actually trying to calculate it with immersed surface method regarding the stress and normal tensors and pressure, but the results I get do not match with bibliography.
I use as planform area the length of the square which is facing the flow. dynamic pressure also is easy to get.

Can someone explain how to calculate the lift and drag forces in a simple way for these conditions??

Thank you in advance