Hello there,

I'm trying to run a VOF animation sequence (this is my first VOF problem). I have two phases and have set the second at a value of '1' and the first phase at '0'. When viewing the animation sequences, instead of seeing a variable change in the displacment of the liquid over time, phase 1 remains at '0' and phase 2 remains constant at the '1' value. My question would be, how do i set the model to give me an animation of variable VOF contours so that i am able to look at the mixing / displacement of the liquid over time?

very many thanks for any suggestions you can offer, thanks, gary.

Are you sure you're solving that correctly? it might not be the postprocessing issue as you don't see any change in the variables. I would check out the boundary and initial conditions again to see if they are correct.

Cheers

Hello Amir.

Thanks for your reply. I'm a beginner with FLUENT so perhaps i am going wrong somewhere. I have a container with one inlet at the bottom and one outlet at the top. I am filling the container with fluid A from the inlet and then displacing fluid A, with Fluid B using the same inlet, forcing fluid A out of the outlet at the top. Fluids have the same density.

I have tried following several tutorials which tell me to assign a volume fraction of '1' to the secondary phase (Fluid B in my case). Does this sound like the correct procedure to you?

Thank you for your time and help! Gary.

You're welcome Gary, The procedure is correct. The volume fraction of fluid B should be set as 1 in the inlet boundary condition but be careful of that in initial condition. it should be set to zero when you initialize the case. I don't see any other point than that. I would recommend you to start off with Implicit VOF as it's easier to get convereged.

Amir

Hello again Amir,

Thanks for the reply but i'm a little confused. I can see where to set the value to '1' in the boundary conditions, but i don't understand what you mean by changing it to '0' when i initialize the problem. Is there a seperate window? or do i have to set the '1' value in the boundary conditions twice? If you have the time to explain the process, it would be greatly appreciated.

thanks again, Gary.

ok sure, The boundary condition window appears in

Define -> Boundary Conditions

but the Initial condition appears in

Solve -> Initialize

that's where you should set the Volume Fraction of fluid B to 0 as there's no B fluid in the tank when you start your simulation.

Hope it helps Amir

thanks very much, i'll give it a try. gary