Regarding problem with the buoyantBoussinesqPimpleFoam solver.

tintintk · March 21, 2018, 08:38

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.

clapointe · March 22, 2018, 21:41

Try an inletOutlet condition for your velocity at the outlet.

Caelan

piu58 · March 23, 2018, 00:57

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.

tintintk · March 26, 2018, 01:20

Quote:

Originally Posted by piu58

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.

tintintk · March 26, 2018, 01:20

Quote:

Originally Posted by clapointe

Try an inletOutlet condition for your velocity at the outlet.

Caelan

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

March 23, 2018, 00:57		#3
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	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. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[ANSYS Meshing] Help with element size	sandri_92	ANSYS Meshing & Geometry	14	November 14, 2018 07:54
mesh.update problem in a new FSI solver	ICL	OpenFOAM	0	October 8, 2011 14:16
Compilation problem after modifying a solver.	PetSul	OpenFOAM Running, Solving & CFD	2	October 1, 2009 17:28
patching problem unsteady solver	yellow-stuff	Main CFD Forum	0	September 25, 2009 01:26
Coupled solver energy equation problem	lucioantonio	FLUENT	0	April 3, 2009 10:21

March 22, 2018, 21:41		#2
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 14	Try an inletOutlet condition for your velocity at the outlet. Caelan