I did the flowing:
1] Geometry is a pipe component with 5cm outer diameter, 200cm vertical and 200cm horizontal with 90 deg bend
2] Splited the inlet surface(edge) into two halves and assigned Air-Inlet and Water-Inlet respectively.
3] The other end I assigned Pressure-Outlet
4] Setting up- general: Y(m/s2) = -9.81. Transient, Planer, Pressure-Based and Absolute were checked.
5] Multiphase model: Volume of Fluid, 2 phase.
Implicit Body Force, sharp and explicit (vol fractn formulation) checked. Phase interaction= (Surface tension= 0.072)
6. Turbulence model: K-Omega.
K-Omega model - SST
Materials: Air, Water
Operating pressure: 101325Pa
Operating density: 1.225kg/m3
7] Boundary condition: air = 10m/s, water = 2m/s, volume fraction for air at inlet = 1. I also tried vol fraction for air = 0.5.
8] Solution method = SIMPLE. I also tried PISO.
9] Solution control: Under-Relaxation Factors left as default
10] Residual monitor: Reduced convergence to 1e-06.
11] Initialised and Patch (note volume fraction: 0.5 or 1).
12] Run calculation: Time step size: 0.001 and 0.0001. Number of time steps: 1000 and 5000.
Summary: Did not generate slug flow. Global Courant Number greater than 250 always coming even after reducing time step.
Pls how can you be of help. Been running this simulation over the weekend.
I will appreciate your kind help and contribution.