# Convergence problem

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July 20, 2022, 07:32
Convergence problem
#1
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I want to simulation fume hood leakage problem and using k model.
boundary condition
inlet pressure inlet= 0 p
sup1,2 velocity inlet= 1.37 m/s
outlet mass flow outlet= 0.516 kg/s

but it can't convergence.
and show this message Reversed flow on 247 faces (2.6% area) of pressure-inlet
plese help me
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July 20, 2022, 09:56
#2
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Quote:
 Originally Posted by Yuan0218 I want to simulation fume hood leakage problem and using k model. boundary condition inlet pressure inlet= 0 p sup1,2 velocity inlet= 1.37 m/s outlet mass flow outlet= 0.516 kg/s but it can't convergence. and show this message Reversed flow on 247 faces (2.6% area) of pressure-inlet plese help me
You can select prevent reverse flow option in the pressure inlet.

July 20, 2022, 11:40
#3
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Quote:
 Originally Posted by Indra You can select prevent reverse flow option in the pressure inlet.
But I want to observed inlet leakage

July 20, 2022, 11:43
#4
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Quote:
 Originally Posted by Yuan0218 But I want to observed inlet leakage
Right, we'll reversed flow shouldn't be the cause for no convergence. Can you show me your solution methods? Try changing to coupled and using pseudo time step method. Also not sure how good your mesh is, but try switching to k-w sst. If you want to use k-e model, use Realisable k-e with enhanced wall treatement.

July 20, 2022, 22:38
#5
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Quote:
 Originally Posted by Indra Right, we'll reversed flow shouldn't be the cause for no convergence. Can you show me your solution methods? Try changing to coupled and using pseudo time step method. Also not sure how good your mesh is, but try switching to k-w sst. If you want to use k-e model, use Realisable k-e with enhanced wall treatement.
this is mesh qality

what is pseudo time step
I trying to add pseudo time step but the continuity still in 1e+00
I used your suggest is this correct?

my english is not good sorry
thank you for answering my question
Attached Images
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July 21, 2022, 04:14
#6
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Quote:
 Originally Posted by Yuan0218 this is mesh qality what is pseudo time step I trying to add pseudo time step but the continuity still in 1e+00 I used your suggest is this correct? my english is not good sorry thank you for answering my question
your continuity is below one in the image you sent me. It seems to be going down, run it for longer. You haven't run it for long enough, you might also wanna add a monitoring point in your simulation.

If it still doesn't converge try reducing pseudo time step from 1.

August 24, 2022, 05:17
#7
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Quote:
 Originally Posted by Indra your continuity is below one in the image you sent me. It seems to be going down, run it for longer. You haven't run it for long enough, you might also wanna add a monitoring point in your simulation. If it still doesn't converge try reducing pseudo time step from 1.
Sorry, I have a question, what is a pseudo time step

 Tags convergence in fluent, fume hood