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garima chaudhary October 9, 2007 02:08

boundary condition_vof model
Hi all

I have a query regarding the selection of type of boundary condition as per the requirement needed for the system(simulating rotor zone of centrifugal contactor using VOF Model). In the domain water is the secondary phase and air is the primary phase. In my system at one of the boundaries of the rotor i need only water to escape out(in case no backflow occurs nad even if a fraction of water returns back the net flow of water shud be out at this boundary). At this boundary no air should leave or enter the domain since for air entry or outlet i already have another boundary in the domain. Moreover, at this boundary the pressure shud be radially distributed according to the centrifugal acceleration.

In need of above the mentioned specifications, I found Pressure_outlet boundary condition to be the most appropriate since it wud radially distribute the pressure but the problem is that when asked for specifying the backflow volume fraction at that boundary of secondary phase, I specified it as 1. Now, THe issue is that at that boundary instead of net outflow of water there is net backflow into the domain which is against my requirements. However,the need that no air shud leave or enter at that boundary is being satisfied.

So plz guide me regarding this issue, can i have another boundary condition which satisfies all these three needs:

1.pressure shud be radially distributed according to the centrifugal acceleration. 2. no air (i.e. primary phase) should leave or enter the domain at this boundary 3. at the boundary there shud be net outflow of water(i.e. secondary phase) even though backflow occurs.

REgards Garima

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