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-   -   How to output the Nusselt number (http://www.cfd-online.com/Forums/openfoam-post-processing/117357-how-output-nusselt-number.html)

liuchaofu May 7, 2013 05:12

How to output the Nusselt number
 
I calculate a jet cooling problems use Openfoam,Then I use the Tecplot post-processing,But I can't output the Nusselt number,or the heat transfer coefficient。Who can help me?

Tushar@cfd May 7, 2013 07:56

Quote:

Originally Posted by liuchaofu (Post 425789)
I calculate a jet cooling problems use Openfoam,Then I use the Tecplot post-processing,But I can't output the Nusselt number,or the heat transfer coefficient。Who can help me?


Well, you can output the variable using utility, please refer the following link for more information...
http://www.cfd-online.com/Forums/ope...timesteps.html

:)

liuchaofu May 8, 2013 09:26

Thank you for your reply.Because I am a newbie on OpenFoam,I only can output the temperature and speed using Tecplot.Can you tell me what variables wo should output to get Nusselt number and the methods.Thank you .

liuchaofu May 8, 2013 09:33

I have to OpenFoam version 2.1.1. I want to use the wall heat flux function.But when I enter this command.It shows this function could not be found.How should I set.Because I is the isothermal wall condition.I need to output the wall heat flux to calculate heat transfer coefficient

Tushar@cfd May 8, 2013 09:44

Quote:

Originally Posted by liuchaofu (Post 426101)
I have to OpenFoam version 2.1.1. I want to use the wall heat flux function.But when I enter this command.It shows this function could not be found.How should I set.Because I is the isothermal wall condition.I need to output the wall heat flux to calculate heat transfer coefficient


In the weblink:
http://www.cfd-online.com/Forums/ope...timesteps.html

Check this code:
###################
volScalarField gradT ( IOobject ( "gradT", runTime.timeName(), mesh, IOobject::NO_READ, IOobject::AUTO_WRITE ), mesh, dimensionedVector ( "gradT", T.dimensions()/dimLength, 0 ) ); label patchi = mesh.boundaryMesh().findPatchID("myPatch"); gradT.boundaryField()[patchi]=T.boundaryField()[patchi].snGrad(); runTime.write();

#####################

This is similar to the $utility/Postprocessing/wall/wallGradU file.
Copy this file and make new wallGradT file.
You need to put T instead of U, as mentioned above. Then try to compile the same. After you finish with this, run the utility in the case folder.

:)


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