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Regarding problem with the buoyantBoussinesqPimpleFoam solver.

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Old   March 21, 2018, 08:38
Default Regarding problem with the buoyantBoussinesqPimpleFoam solver.
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Vishwajit Kumar
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Hello everyone.

I am trying to simulate flow in a nozzle using the buoyantBoussinesqPimpleFoam solver. But at the outflow i am getting back-flow. I have tried all the possible boundary condition.
I am also attaching the case file for the reference and the screenshot the problem that i am getting.


the screen shot attached shows the problem at the outlet..where instead of getting the fully developed profile i am getting two recirculating zones.

Thank you in advance.
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File Type: png nozzleflow.png (11.5 KB, 19 views)
Attached Files
File Type: gz nozzleflow.tar.gz (4.0 KB, 2 views)
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Old   March 22, 2018, 21:41
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Try an inletOutlet condition for your velocity at the outlet.

Caelan
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Old   March 23, 2018, 00:57
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Uwe Pilz
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If you use an outflow b.c. you should have an outflow stream there: The flow should not contain any backflow components. The flow property you set (zeroGradient) should be realized by the flow itself.

I recommend to simulate a longer region for stabilizing the flow. Usual, 10 times the size of obstacles is the required minimum. You don't have an obstacle, so I recommend 10 times the size of the large eddies.
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Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)
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Old   March 26, 2018, 01:20
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Quote:
Originally Posted by piu58 View Post
If you use an outflow b.c. you should have an outflow stream there: The flow should not contain any backflow components. The flow property you set (zeroGradient) should be realized by the flow itself.

I recommend to simulate a longer region for stabilizing the flow. Usual, 10 times the size of obstacles is the required minimum. You don't have an obstacle, so I recommend 10 times the size of the large eddies.

Thank you for the suggestions. I will try to implement it.
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Old   March 26, 2018, 01:20
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Quote:
Originally Posted by clapointe View Post
Try an inletOutlet condition for your velocity at the outlet.

Caelan

I have also tried this boundary condition but of no use.
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