Help on periodic boundary condition
 

Hi everyone!

I am trying to simulate a 3D incompressible, laminar flow in a micro square duct. Here are input parameters:

1. Duct size: 200x200x200 micrometer.
2. Water is working fluid with 998kg/m3 in density and 0.001 kg/m.s in viscosity.
3. Pressure drop: 200000 Pa/m

Periodic boundary condition was applied at inlet and outlet of the duct. However, when I specified the pressure drop and solved (I chose to specify the pressure drop in spite of mass flow rate), it converged after only 1 iteration and the wall shear stress is always zero. It's impossible but I don't know where this issue comes from.

I highly appreciate for any help.