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Old   June 2, 2005, 12:00
Default VOF variable contours
  #1
gh
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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.
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Old   June 2, 2005, 13:41
Default Re: VOF variable contours
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Amir
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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
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Old   June 2, 2005, 13:47
Default Re: VOF variable contours
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gh
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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.
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Old   June 2, 2005, 14:24
Default Re: VOF variable contours
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Amir
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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
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Old   June 2, 2005, 14:54
Default Re: VOF variable contours
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gh
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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.
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Old   June 2, 2005, 15:24
Default Re: VOF variable contours
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Amir
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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
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Old   June 2, 2005, 17:33
Default Re: VOF variable contours
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gh
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thanks very much, i'll give it a try. gary
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