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March 5, 2019, 23:08 |
Nusselt Number Calculation by OpenFoam
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#1 |
Member
Mondal
Join Date: Sep 2018
Location: Canberra ACT
Posts: 68
Rep Power: 7 |
Dear Foamers,
What is the process of calculating Nusselt number from OpenFoam simulations. I am simulating natural convection along a vertical plate using buoyantPimpleFoam (OpenFoam Version 3.0.1). Is it possible to find it by putting function inside the controlDict? Any help will be appreciated. Thank You in advance... Cheers, Razon |
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March 10, 2019, 00:46 |
Nusselt number calculation
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#3 | |
Member
Mondal
Join Date: Sep 2018
Location: Canberra ACT
Posts: 68
Rep Power: 7 |
Quote:
Hi Eldrael, First of all, thank you for your response. I tried several times in the above process but could not successfully compiling. Here I attached my edited NusseltCalc file and error image. Can you help me please? Cheers, Razon |
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March 10, 2019, 22:00 |
Function object calculation of Nu
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#4 |
New Member
Join Date: Mar 2016
Posts: 8
Rep Power: 10 |
Hello Mondal:
I am sorry to say I am not very familiar with the solver that you are posting, C++ nor OpenFOAM coding. Thing is that you may not need to do it. Let's review how to calculate the Nusselt: Nu= h L/ k; where the only thing not known in here is the h coefficient, as L is chosen by the user and k is a physical property of the fluid. h coefficient has an arbitrary definition as the number fulfilling that Q=hA(Tfluid-Twall). Tfluid is set as a "bulk" temperature, so you choose it yourself. If you are in an incompressible solver you can calculate h by using typing HTML Code:
*typeHereYourSolver* -postProcess -func wallHeatTransferCoeff The alternative is to use function objects to:
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March 11, 2019, 08:03 |
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#5 |
Senior Member
Agustín Villa
Join Date: Apr 2013
Location: Alcorcón
Posts: 313
Rep Power: 15 |
Hi,
I normally do it later, during the post processing. What you will need to extract is the wall temperature gradient. |
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March 12, 2019, 20:21 |
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#6 | |
Member
Mondal
Join Date: Sep 2018
Location: Canberra ACT
Posts: 68
Rep Power: 7 |
Quote:
Thank you for joining in this conversation. Actually, I want to calculate the Nusselt number along the wall or from the whole computational domain. How did you do that? If I want to calculate the nusselt number for the whole domain, what is process of doing that after simulation? Can you please explain it? Cheers, Razon |
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March 13, 2019, 04:10 |
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#7 | |
Senior Member
Agustín Villa
Join Date: Apr 2013
Location: Alcorcón
Posts: 313
Rep Power: 15 |
Quote:
Hi Razon, what I did, I developed a functionObject to get the wall temperature gradient (starting from the wallShearStress one, you have few modifications to do), and using it you can get the Nusselt as where L is the wall coordinate. I suppose that, for the Nusselt within the fluid (does somebody uses that quantity) you should use the temperature gradient there. |
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