solution is not getting converged

Nijanthan · July 16, 2013, 04:10

am having pressure inlet of 83 bar,where its inlet diameter is of 9.05mm. also pressure outlet of 43 bar with outlet dia of 2.05mm.
my problem is if i monitor the mass flow rate in inlet it is around e15. because of which my solution is getting diverged and also am having turbulence viscosity limited error. how do i rectify it ???
Note: msh count is of 6.4million and it has interfaces in it.

vasava · July 22, 2013, 09:40

83 bar (almost 38 atm) and a diameter of mere 9 mm looks an unrealistic problem. What is the application of your problem?

Nijanthan · July 24, 2013, 05:52

well its kind of water injector. sorry sir cant tel rest of it coz its confidential

vasava · July 24, 2013, 08:37

Ofcourse with that high pressure you would get high mass flow rate. The turbulence viscosity error is because of coarse mesh, bigger time step or both.

upeksa · July 24, 2013, 21:35

I'm not sure, but I think that the problem could be that the conditions of pressure-inlet and pressure outlet, it might be too restrictive.
First try with mass-flow-inlet and presure outlet and if it doesn't still work, try mass-flow-inlet and outflow.
Also use the first order discretization and make sure you have set up your case properly, specially make sure your material choice is the correct one.

Best regards.

vasava · July 25, 2013, 02:42

Still my concern is the enormous amount of pressure and the tiny little outlet. You would need billions of mesh elements just to keep the courant number low.

There must be some other detail you can spare.

July 16, 2013, 04:10	solution is not getting converged	#1
Nijanthan New Member Nijanthan Thinakaran Join Date: Jul 2013 Posts: 15 Rep Power: 13	am having pressure inlet of 83 bar,where its inlet diameter is of 9.05mm. also pressure outlet of 43 bar with outlet dia of 2.05mm. my problem is if i monitor the mass flow rate in inlet it is around e15. because of which my solution is getting diverged and also am having turbulence viscosity limited error. how do i rectify it ??? Note: msh count is of 6.4million and it has interfaces in it.

July 24, 2013, 05:52	injector	#3
Nijanthan New Member Nijanthan Thinakaran Join Date: Jul 2013 Posts: 15 Rep Power: 13	well its kind of water injector. sorry sir cant tel rest of it coz its confidential

July 24, 2013, 08:37		#4
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	Ofcourse with that high pressure you would get high mass flow rate. The turbulence viscosity error is because of coarse mesh, bigger time step or both. Last edited by vasava; July 25, 2013 at 02:39.

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July 22, 2013, 09:40		#2
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	83 bar (almost 38 atm) and a diameter of mere 9 mm looks an unrealistic problem. What is the application of your problem?

July 24, 2013, 21:35		#5
upeksa Member Join Date: Jul 2013 Posts: 80 Rep Power: 13	I'm not sure, but I think that the problem could be that the conditions of pressure-inlet and pressure outlet, it might be too restrictive. First try with mass-flow-inlet and presure outlet and if it doesn't still work, try mass-flow-inlet and outflow. Also use the first order discretization and make sure you have set up your case properly, specially make sure your material choice is the correct one. Best regards.

July 25, 2013, 02:42		#6
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	Still my concern is the enormous amount of pressure and the tiny little outlet. You would need billions of mesh elements just to keep the courant number low. There must be some other detail you can spare.