Why is fixedFluxPressure more stable ?
I recently an few multiphase scenarios using interFoam and found that fixedFluxPressure is more stable for the simulation than zeroGradient. What might be the issue for this ?
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Hi HR,
At the 11th OpenFOAM Workshop there was a Training Course with the title "Learning how to use free surface flows in OpenFOAM 3.0" by Victoria Korchagova. This course is the only material that I found that explains this boundary condition. Is it for OF version 3, but I think that it also applies to newer versions. You can download the course material in this page: https://openfoam-extend.sourceforge....s/courses.html |
The OpenFOAM user guide also mention it, despite not giving much details:
Quote:
There are also on old thread here discussing it: https://www.cfd-online.com/Forums/op...xpressure.html My personal experience with buoyantSimpleFoam is that I get a flowrate through the walls when using zeroGradient and it does not happen with fixedFluxPressure. Yann |
Hi,
This is because when you’re solving for p, zero gradient isn’t the correct boundary condition. Consider additional forces, such as gravity: if you zero gradient the pressure, such terms will give you flux through a wall. Fixed flux pressure compensates for it to achieve zero flux: you get a pressure gradient on the wall to balance all other flux contributions. Hrv |
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