Hello,

I am trying to implement the model describing flows of two fluids that do not mix (like water and oil for example). They have different material parameters as well (density, viscosity etc.) If it would be just one fluid, I would just implement Navier-Stokes equations. However, for two fluids I need somehow keep track, of which fluid is where since it changes the parameters of Navier-Stokes. I was trying to do it by introducing a scalar variable that is 0 for the first fluid and 1 for the second, and updating this variable according to the velocity field. However, this approach in my case is very unstable, so I didn’t succeed.

Does anyone now existing examples of modeling two unmixing fluids? Or someother method I should try? Thank you!