[yufeiai]

Hi guys,

I am simulating an oscillating heat pipe in FLUENT, which is a capillary tube arranged in a serpentine manner and forms a close loop. It doesn't have flow inlet and outlet. It is partially filled with water. Water evaporates and the vapor rises under the force of a heater at the bottom of the pipe. Vapor then condensed at the top of the heat pipe. Therefore it forms a two-phase flow in the pipe.

I'm wondering how I should deal with boundary conditions. There is motion with the fluid flow, but actually no inlet or outlet in reality. I'm not sure if I should define a velocity inlet or pressure outlet somewhere？

Also can I define a heat flux at the walls at bottom without UDF functions?

Thanks for any comment or suggestion!