Density and Viscosity calculation for Poiseuille Flow


Is there any way to calculate density in Poiseuille flow example (2d/3d) ?
My aim is to calculate viscosity in same example for LJ fluids .
I have seen few density calculations but I’m not sure how to relate with real density terms and calculation for Poiseuille flow.

You can calculate a density profile for any system by using
the fix ave/chunk and compute chunk/atom commands.