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Some questions about buoyantBoussinesqPimpleFoam |
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March 19, 2018, 13:10 |
Some questions about buoyantBoussinesqPimpleFoam
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Join Date: Jun 2017
Posts: 58
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I'm trying to make a solver similar to bBPF, but with some additional forces. I'm having difficulty, so I'm trying to start out by modifying pimpleFoam to match bBPF, reasoning that if I can get these modifications to work, I can understand how to add additional forces.
To do this I'm referencing the source code, along with the detailed explanation of the buoyantBoussenesqPisoFoam (http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam). My first question is about the buoyancy force term. In the piso version, it is added to the momentum predictor as: Code:
fvc::interpolate(rhok)*(g & mesh.Sf()) Code:
rUAf*fvc::interpolate(rhok)*(g & mesh.Sf()); Code:
- ghf*fvc::snGrad(rhok) Code:
phig(-rAUf*ghf*fvc::snGrad(rhok)*mesh.magSf()); My other question is about adjustPhi. As I understand it, adjustPhi will adjust mass outflow to ensure continuity across adjustable outlets like boundaries of zeroGradient for U within a certain tolerance. pimpleFoam contains this adjustPhi, however, bBPF does not. Why is this? I'm using the hotRoom tutorial as a testcase to compare my own version of the code to bBPF. If I leave the adjustPhi term in, I immediately get a mass discontinuity error. I've discovered the error is linearly proportional to the temperature advantage of the faces set by setFields, and the solver executes fine if I remove this temperature advantage, so clearly it is something to do with that. If I remove adjustPhi from the code entirely, the solver executes, albeit with nonphysical results, but I guess that may be to do with subsequent errors. I also tried modifying bBPF to include an adjustPhi term, and when I used it to execute hotRoom, it also met with similar mass discontinuity errors. Apologies for the long post. In short, my questions are: 1) Why is the buoyancy term in bBPF negative, whereas in piso, it is not? 2) Why is adjustPhi not present in bBPF? Thank you |
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