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Turbulent flow in tube and laminar flow in annulus

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Old   March 9, 2013, 08:38
Default Turbulent flow in tube and laminar flow in annulus
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shahab
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Hi.I want to model heat transfer in a double pipe that turbulent flow of water is in the inner tube and laminar flow is in the annulus.how can i do this with fluent?
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Old   March 9, 2013, 08:46
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If you can keep Yplus below 1, then try transition model.

Fluent has option to model both option in same model. You just need to define two fluids I guess.

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Old   March 9, 2013, 09:01
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thanks for your help but my problem is in selecting viscous model turbulent and laminar flow simultaneously in tube an annulus respectively.
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Old   March 9, 2013, 14:53
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Can you elaborate your problem a little bit more, because i think you need to specify either two different inlet boundary conditions or the alternate option i can tell you seeing your geometry or computational domain.
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Old   March 10, 2013, 06:41
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here's the more details about problem.There is a double pipe that hot water by turbulent flow goes through the inner tube and cold water by the laminar flow goes through annulus (between outer tube and inner tube) and heat transfers between two fluids now i want to model this by fluent and wanted to know how to choice viscous model for each region of fluid.
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Old   March 10, 2013, 07:16
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Hi mozafarie,
thanks for giving more information.
The working fluid is water. You need to specify the materials for the inner and the outer pipe. These materials are assumed to have the same density and heat capacity , but obviously different thermal conductivities.

You need to change the thermal conductivities of the two pipe surfaces that you model as solid. In addition you use two different fluid b.c's i.e one for the cold fluid letu say 20C
Also turn on the energy equation option and choose the Reliazable k-epsilon turbulence model. You donot have to worry about how you specify the turbulent and laminar region this will be taken care by the boundary condition you specify and the eddy viscosity turbulence model will detect the laminar and turbulent flow internally.

Do remember that you should use pressure based solver and specify the fluid material properties i.e water in your case properly like density, cp, thermal conductivity and viscosity.

Define your first fluid inlet b.c for cold flow . That means velocity inlet and specify the velocity in the momentum tab followed by the choosing turbulent specification method as turbulent intensity and hydraulic diameter. Secondly choose the thermal tab and specify the temperature. Similar approach for the hot flow should be followed.

For the walls of the pipe under the thermal tab you need to choose 0 W/m2.

I hope this helps and wish you good luck.
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Old   March 10, 2013, 07:31
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Hi taxalian.
I appreciate it.My problem was solved for your good help.
thanks a lot
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Old   March 10, 2013, 07:56
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ok thats good to know at least its helpful to you.

best of luck
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Old   November 25, 2014, 02:58
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Quote:
Originally Posted by mozafarie View Post
Hi taxalian.
I appreciate it.My problem was solved for your good help.
thanks a lot
sir will u give me jou file of gambit and case and data file of fluent i have also similar type proble sir my mail i m9713001413@gmail.com
sir please help me
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