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August 21, 2012, 08:44 |
Laminar or Turbulent model
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#1 |
Member
prince
Join Date: Jun 2011
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Hello Friends
How to model a system where flow is turbulent at one part of system and rest part flow is laminar. |
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August 23, 2012, 03:13 |
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#2 |
Senior Member
Vaze
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Hi
This is possible with UDF where you have to tell solver that up to finite length of the domain turbulence model will work and in rest of the domain another model. I have not yet tried such UDF but it can be possible. Best wishes Mvee |
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August 23, 2012, 07:09 |
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#3 |
Senior Member
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Transition is taking place from laminar to turbulent in your system or you have two different flows one laminar and one turbulent at different parts of your system? what exactly is your problem?
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August 23, 2012, 07:10 |
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#4 |
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Richard Parker
Join Date: Jul 2012
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Simply solve all with a turbulent model. A turbulent model accounts for turbulence, but this does not mean you are assuming the flux is turbulent. It might as well be laminar.
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August 23, 2012, 07:25 |
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#5 |
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cfdnewbie
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That would be unwise to do. The standard turbulence models (I am assuming you are doing RANS) add viscosity to the flow, even in the laminar regime. When using a additional turbulence model in the laminar region, you will likely get execessive dissipation there...
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August 23, 2012, 07:32 |
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#6 |
Member
prince
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@ CFD seeker :- Transition is taking place from turbulent to laminar. My problem is like this.
I have a pipe on which 10 nozzles are mounted. This pipe system is to recirculate water in rectangular pool. Water through nozzles goes into pool and there is outlet for water inside pool. Flow is turbulent inside the pipe and when it passes through nozzle but re- circulation inside pool is laminar. I am expecting at certain height the transverse velocity should be almost zero but i am not getting the desired result. @ MVEE :- I will try the UDF way. Thanks.. Will let you know if it works. @ Richard Parker :- I am not very clear what did you suggest. Please can you elaborate a little.. |
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August 23, 2012, 07:37 |
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#7 | |
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Quote:
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August 23, 2012, 08:05 |
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#8 |
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Richard Parker
Join Date: Jul 2012
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Perhaps it is not necessary to write an UDF. Fluent has the capability of defining a laminar zone, where turbulence equations are not solved. You just have to define the zone in the mesh and then mark is as a laminar zone in the Fluid panel of the GUI. Have a look here. (I must say that I've never done it myself, but looks promising).
About the consequences of solving laminar flows with a turbulent model whe have a good old post with a very knowledgeable insight. |
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August 24, 2012, 01:46 |
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#9 |
Member
prince
Join Date: Jun 2011
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Thank all of you for interest..
It has been useful |
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