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 mateus May 2, 2003 03:59

continuity equation for the mixture

Hi!

I posted this message some time ago on fluent forum but iīve got no responce. So iīll try my luck here...

Iīm dealind with cavitation problem with so called mixture model. Itīs 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

Itīs 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 itīs 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. - shouldnīt mass transfer be included here????