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Jet cross flow in a cylindrical mesh

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Old   March 12, 2012, 11:16
Default Jet cross flow in a cylindrical mesh
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Charlie
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I have a finely meshed cylinder (good checkMesh). There is a jet flow of water entering the bottom of the cylinder and a cross flow of air from the sides of the cylinder. I had to split the two cylinder walls in two (for an inlet and outlet). The jet alone works, but when introducing the cross flow it crashes and U blows up in the solution but the residuals all look fine (1e-05 initial residual). But the adjustable time step causes the time step to go amazingly low. I can't find the right BC's for the inlet and outlet of the crossflow patches and have tried near everything. I think the problem is that the two patches are wrapped around the cylinder and meet on both ends, this must cause a problem when forcing certain BC's.

Any suggestions as to which BC's i should use on the two side patches (outer circumference split evenly in two) to have a 40 m/s cross flow.


thank you
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Old   March 13, 2012, 03:03
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Niels Nielsen
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Hi

Can you please post a sketch or the CAD-file or the case?

Also some info on the actual BC the output of the last iterations schemes and solver would help us to help you.

This will make it a lot easier to help as the description you give doesn't give a clear picture unless you work with cross-flow problems on a daily basis.

Best
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