continuity equation for the mixture

mateus

Hi!

I posted this message some time ago on fluent forum but i´ve got no responce. So i´ll try my luck here...

I´m dealind with cavitation problem with so called mixture model. It´s very simmilar to VOf model. Anyway the problem is with continuity equation with the mixture.

d/dt(rho_m)+nabla(rho_m*v_m)=mass transfer

It´s equation 20.3.1 in fluent manual. index m means mixture (all the parameters of each phase - like velocity and density are averaged to a single mixture phase).The question is how can there be mass transfer between phases inluded in this equation if it´s averaged for the mixture????

The other equation is volume fraction equation for secondary phase (20.3.15) To get the void fraction of each phase in a cell fluent solves this equation:

d/dt(alpha_k*rho_k)+nabla(alpha_k*rho_k*v_k)=0

where alpha_k is the volume fraction of k-th phase. - shouldn´t mass transfer be included here????

please help

regards MATEUS