Hi guys I am currently using Comsol to model a single rectangular channel, a typical one found in a fuel cell (with symmetry boundary). Dimension of the inlet and outlet area is of the order 10e-3 and the length of the pipe is 0.1 m. I am having difficulty getting the expected result. The pressure drop vs velocity of fluid flow should be a curve that can be mapped by a second order quadratic equation (as the velocity increases, the pressure increases with increasing rate) But no matter how I try I keep getting a relationship that is close to linear, and only very slightly curved. Here's what I've done, tried different solvers, played around with the meshing, changed the viscosity, but the result is the same, an almost linear graph, which does not fit the expectation. Can anyone who is familiar with Comsol offer any advice regards to this problem? Thanks in advance.