Weighted average volume fraction

Yasser

Hello,

I am simulating 2-phase solid-liquid flow in mixing tank using Eulerian model. My study concentrate on the concentration of solids in the tank. I have no injections of solids or liquid in the tank (the impeller mixes the 2 phases).

I assumed an initial homogenous mixture with solid volume fraction of 0.04 by patching this value before iteration.

After the solution converged, i found the Weighted average volume fraction is lower than 0.04, it was equal to 0.023.

I tried to turn off the volume fraction equation but,When i turned the volume fraction equation off, the mixture became homogenous as initialized and no particle distribution obtained.

how can i fix the volume fraction of the solid in the whole tank while the concentration still can change??

Thanks for help