How to find the total pressure gradient for a multiphase (liq-gas) bubble flow in a pipe?
My aim is to validate my CFD model by comparing the pressure gradient obtained from the simulation to semi-empirical equations derived by others. I have simplified the problem to a 2D-planar case. I am using the VOF model and the pipe has some inlet mass flow for both liquid and gas phases. In addition the pipe is open to the atmosphere at the top, and gravity is imposed over the pipe.
However, I am having trouble trying to find the total pressure gradient in a vertical multiphase pipe flow. Because there is pockets of gas throughout the pipe, the pressure is varying quite a lot (See image below for ref.)
Thank you very much for reading. I am greatful for any comments or recommendations.