What's the difference between "FluidPressureOutlet3D" and "addPressureBoundaryNP"?

Hi everyone,

I found a boxprocessingfuncion called “FluidPressureOutlet3D”. Code comments said that it copies unknown populations plus imposes constant pressure. I wonder what the difference is between it and the “addPressureBoundaryNP(domain, lattice, neumann)”?

best wishes,

steed188