Learning Forum

[tk2501]

Hello everyone,

I'm relatively new to CFD simulation with Ansys.

I want to simulate a three-phase mixture consisting of Water, a liquid that is not soluble in water, and air in a bubble column. The air is only there to mix the two liquids which are immiscible.

Can I simulate something like this with the Euler model, and what do I need to pay attention to (model selection, forces, coefficients, etc.)?

Thank you 🙏

[Rob]

You can. Is air a low volume fraction of bubbles, ie a sparger, or something else? Multiphase modelling is "easy"; choosing the right models is somewhat less so. 

I thought acid was, by definition, water soluble? 

 

[tk2501]

It is a jet nozzle. The volume flow of air is many times higher than that of liquids.

You are right, acid is by definition soluble in water. It was only meant to be an illustrative example. I have now adjusted it so as not to cause any further confusion. 

Which model would be the right one for this? I made my first attempts with SST k-omega and standard k-epsilon. 

[Rob]

Those are turbulence models, so whilst useful aren't likely to dominate the flow effects. 

Do you expect the two liquids to mix (as an emulsion) or retain a defined free surface? Or both?  Check the content in Learning and read the Fluent manual to work out what questions to ask. 

[tk2501]

Both liquids will have a clear interface. Would you recommend the laminar model?

I will take a look in Learning 👍

[Rob]

Is the flow laminar? 

Focus on Eulerian and VOF as the two main models for what you may need. Neither is "best" overall but one or other will be better for your application.