# Two Phase Pressure Loss Calculations

When two-phase liquid gas flow occurs in pipes, many different flow patterns are created, depending on fluid properties, the relative rates of each fluid and the pipe inclination. There are large differences in flow behavior between horizontal, inclined and vertical pipe flow. The pressure gradient (pressure loss per unit length) is flow pattern dependent. For a rigorous estimation of two-phase pressure drop we also need to split the pipe into segmental lengths, similar to the approach used in gas pipe calculations. Our pressure loss algorithm dynamically splits the pipe into segments based on an incremental pressure change. The user can select from any one of eight available models: ▪Whalley Criteria (uses Friedel, Chisholm or Lockhart Martinelli, selection of method is made by FluidFlow according to the criteria of Whalley). ▪Drift Flux Model (2007 correlations). ▪Beggs and Brill (Extended Regions). ▪Friedel. ▪Muller Steinhagen Heck. ▪Chisolm Baroczy. ▪Lockhart Martinelli. ▪Homogeneous Equilibrium Model.