Friction force in Couette flow

Dear LAMMPS users

I want to calculate the friction force applied from water on the upper moving wall in the Couette flow. In this problem, water is confined between two parallel plates and the upper wall moves in x direction while the lower plate is kept stationary. One way which came to my mind is that to multiply p_xy (shear stress on y plane in x direction) by the area of the upper wall. Is this a correct way?



Look in the lit on how people do this type of calculation. This is a typical case of a kinetic friction problem. People who study confined polymers between walls have done this for sure.
Quick names that come to mind: Binder, Grest and Robbins. I am sure all of them have done and published about this type of calculation. I would say right away that your idea is off the board.

Or you could sum the force on wall atoms to get the total
force applied by the fluid to the wall.