[mniknam]

I am simulating two phase (liquid-liquid) turbulent flow in a curved pipe using the VOF model. In single phase incompressible turbulent flow,when we implement time-averaging on momentum equation new terms, known as Reynolds stress, will appear.
when we use VOF model,The momentum equation is dependent on the volume fractions of all phases through the properties density and viscosity.
In some cells, volume fractions may vary with time, and in some cells volume fraction is constant. Does density in momentum equation vary with time ?
The main question is: If we implement time-averaging on momentum equation using VOF model, does any new term appear apart from Reynolds stress (due to time-varying density)?