Calculation of pressure loss for two phase flow in a horizontal or vertical straight pipe for an overall flow regime considering frictional, momentum and geodetic pressure loss.
Generally the pressure loss for two phase flow in a horizontal or a vertical straight pipe can be calculated for the following fluid flow regimes:
Horizontal fluid flow [(a) bubble flow, (b) stratified flow, (c) wavy flow, (d) slug flow, (e) annular flow]:

Vertical fluid flow [(a) bubble flow, (b) plug slug flow, (c) foam flow, (d) annular streak flow, (e) annular flow]:

function dp_twoPhaseOverall_DP
extends Modelica.Icons.Function;
input Modelica.Fluid.Dissipation.PressureLoss.StraightPipe.dp_twoPhaseOverall_IN_con IN_con "Input record for function dp_twoPhaseOverall_DP" annotation(
Dialog(group = "Constant inputs"));
input Modelica.Fluid.Dissipation.PressureLoss.StraightPipe.dp_twoPhaseOverall_IN_var IN_var "Input record for function dp_twoPhaseOverall_DP" annotation(
Dialog(group = "Variable inputs"));
input SI.MassFlowRate m_flow "Mass flow rate" annotation(
Dialog(group = "Input"));
output SI.Pressure DP "Two phase pressure loss";
end dp_twoPhaseOverall_DP;