# How does ANSYS FLUENT model the surface tension in the Eulerian (multi-fluid) model?

I am using ANSYS FLUENT to model a two-phase flow of liquid and gas using the Eulerian model where the surface tension force is included.

In the theory of the VOF model, the surface tension force is added to the momentum equation as a source term. However, in the Eulerian model, we have two momentum equations, one for the liquid and one for the gas.

How is the surface tension force included? is it added to the liquid momentum equation?is it added to the gas momentum equation? is it split between the two phases? If it is split, is it split by two volume averaged factors or two mass averaged factors?

Unfortunately, the theory manual does not mention related information under the Eulerian model theory.

## Comments

Give me some more time for reflection and I will get back to you!

Thanks for your interest. I would be very thankful for you if you could help me.

It is just multiplied with the volume fraction of the phase and applied for each momentum equation set of each phase. So if you add both momentum equations set for two phase flows you will end up with the source term applied for the bulk (like in VOF method). Please bear in mind that as ANSYS Stuff I cannot provide more information about the implementation on this open community.

Thank you so much. That answers my question. That means it is split by two volume averaged factors.

I appreciate your help a lot. Thanks