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Old   September 26, 2005, 13:30
Default Is there a way to setup mass/m
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Ramiro Brito Willmersdorf
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Is there a way to setup mass/momentum point sources? Alternatively, can boundary conditions be assigned to single nodes?

I'm asking because I have a very high speed jet flowing into a very large volume. If I model the inlet as a real inlet, I have to use very small elements (obviously), therefore I have to use itsy bitsy teeny weeny time steps to achieve stability (since there is no local time stepping, as I understand). We are talking element edge sizes from 0.020m to 10m here. (Obviously the mesh is nicely graded.)

If I'm just interested in the global features of the flow, this is not so good, because I have to wait for thousands and thousands of time steps just for the flow information to propagate throughout the domain. I think I could get an adequate solution much faster if I could use a more uniform (with larger elements) mesh.

Would it work to use a non-uniform input profile, with all nodes but one with the velocity I want?

Many thanks!
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Old   November 1, 2005, 11:46
Default Hi, I want to solve an equati
olivier Petit
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I want to solve an equation of momentum with an exterior force F (F doesn't depend on U, it is an volVectorField).

should I make F like a source term (with fvm::Su)?
because when I make :

tmp<fvvectormatrix> UEqn
fvm::div(phi, U)
- fvm::laplacian(mu,U)

solve(UEqn() == -fvc::grad(p))-fvm::Su(F,U) )
I have a bad result.
thanks for your help
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Old   November 1, 2005, 15:20
Default no, you just add -F solve(UEq
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Niklas Nordin
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no, you just add -F
solve(UEqn() == -fvc::grad(p))-F)

did you try that?
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