I have simulated a stationary 2D pipe flow in a 30 mm X 5 mm rectangular domain using the Creeping flow module to solve the incompressible Navier-Stokes equation. The boundary conditions are no-slip wall on top and bottom edge, inlet velocity = 5 mm/s and outlet pressure is 0. I have obtained the results with max. velocity = 7.56 mm/s and max. pressure = 0.52 Pa.
The same simulation was run using weak form instead of using predefined modules. I have constructed the weak form for both continuity and momentum equation. I obtained the same velocity but the pressure distribution was not correct. Maybe there is mistake in my boundary conditions.
What is the mistake I am doing?