assign residual volume fraction
 

Hi
imagine a domain in which all cells are filled with water at the beginning, (t=0) then another fluid is entered to the domain and displaces the water,
if I want that always some water (e.g. 20%) remains in each cell and second fluid can not displace it what should I do?

I really appreciate if you could help me

Control the mass flow of 2nd fluid...calculate the volume of water that should stay in the domain...according to that u control the volume flow of 2nd fluid with different density...

Are you trying to unsteady simulation of two different fluids mixing in a container??

Dear Anandanarayanan
I am trying the unsteady simulation of drainage process in which one fluid is displaced with another one. at first there is just primary phase in all cells. when secondary fluid displaces the primary fluid, it occupies the cells, but I want that some of primary phase remain in each cell (e.g. 20%)

Okay...but how is it possible to make 20% of water to remain in the domain if the secondary fluid is continuously flowing....

Try with low mass flow rate for a certain period....then see volume fraction of water in the domain....

Actually I am using pressure inlet.
I dont think it works. I think I should fix volume fraction of primary phase so that its volume fraction never goes beyond the 20%. but I dont know how!