[esma]

Hi All,
I'm modeling a plunging jet of water on the water surface inside a tank (see the image). I ran my model in Eulerian-MFVOF as well as Mixture model within Fluent. I came to the conclusion that the generated air bubbles require to capture the drag force at the interface with primary phase (water) as recommended in some literature. My problem is the convergence since should the value of bubble diameter be increased to a larger value (e.g 2mm) from its default 0.01mm (image) for the secondary phase, the solution abruptly diverges and crushes. I tried to play with the under-relaxation factors and followed some instructions online but no luck. Just to mention, the mesh size is 0.5mm for the water phase and for the air on top set to 2mm. Appreciate for any tip.

Update:

I realized the Eulerian+MFVOF is more stable compared to Mixture model after increasing the secondary phase diameter to even 4mm. So the simulation is going well even though had some shaky beginning.

[ves]

Try using anisotropic drag, simonin turb. interaction with lim. func., per phase k-w SST, W - cycle pressure, stop criterion for pressure 0.001, another variable 0.01, ILU, agressive coarsening, relaxation coeff 0.2 for all variables, variable timestep from 0.001s to 1e-6 s