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Calculating and Plotting Nusselt Number with ParaView

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Old   May 25, 2014, 19:39
Default Calculating and Plotting Nusselt Number with ParaView
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Hi!
I have been working with OpenFOAM and some GUI (Helyx-OS). Am simulating cases with conjugated heat transfer and I would like to Plot the Nusselt Number with ParaView, however I don't know how to calculate it with OpenFOAM.

I do can calculate the Nusselt Field in ParaView, but I can't Plot it over a line (That's my goal).
At the beginning I downloaded the last version of ParaView because the version of OpenFOAM (sudo apt-get install paraviewopenfoam410) cannot use the "Calculator application" properly. So I downloaded the binary files from www.paraview.org.

Now what I need is to plot the Nusselt Number over a line, but it does not let me do it with my Calculated Nusselt.
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Old   June 8, 2014, 13:40
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Greetings Tom,

I have no idea if you've managed to solve this issue already or not, but if you haven't, please provide more information, namely:
  • What settings did you use for the calculation?
  • What specific filter and settings did you use for plotting?
  • What settings did you use for the plot?
And please provide image snapshots of what you're seeing, because from your brief description, I'm unable to imagine what went wrong.


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Old   April 26, 2016, 09:34
Exclamation finding Nusselt number in paraview
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Good evening Bruno,
i dont have any idea how to calculate derivatives and integrations in paraview.
If you know how to calculate Nusselt number and Mean Nusslet number? please let me know.
Thanks
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Old   April 26, 2016, 14:49
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As far as I know, the Nusselt number can only be calculated on the walls because of its definition:

Nu = \frac{\alpha L}{\lambda}

The heat transfer coefficient \alpha could be calculated using the heat flux q or heat Q:

Q = A \cdot \alpha \cdot (T_{amb} - T_f)

Due to the fact that there has to be an equilibrium of Cell-Center to Face-Center and Face-Center out to air or even another fluid / solid,

Q = A \cdot \lambda \cdot (T_f - T_c)

So finally you know q or Q and you can calculate \alpha. Then you simply can calculate the Nusselt number.
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Old   May 3, 2016, 13:58
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Quote:
Originally Posted by Tobi View Post
Due to the fact that there has to be an equilibrium of Cell-Center to Face-Center and Face-Center out to air or even another fluid / solid,

Q = A \cdot \lambda \cdot (T_f - T_c)

So finally you know q or Q .....
Dear Tobi,

I am new to ParaView, could you explain to me how to get the q or Q values from Paraview? I have a cylinder and need to know the dissipated heat through its external surface.

What I would imagine to do: take temperature value of face-center cell of external surface cells; take temperature of respective volume-center cell; calculate its difference corresponding to a gradient in relation to cell size; do this for all external cells areas (integrate it); muliply by conductivity;

The problem is that I don't know how to do it with ParaView... :P

Thank you!

Regards,

Lisandro Maders

Last edited by Lisandro Maders; May 3, 2016 at 14:22. Reason: better explanation of what I want
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Old   May 3, 2016, 17:39
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I do not know if you can do this with paraview.
You can do it with openfoam tools (wallHeatFlux).
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Old   May 3, 2016, 17:42
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Quote:
Originally Posted by Tobi View Post
I do not know if you can do this with paraview.
You can do it with openfoam tools (wallHeatFlux).
Yes, that's what I am doing. I was hoping there was someway of doing this in ParaView but actually is pretty much easier to do this with the openffoam utilities.

Anyway, cheers!
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Old   May 3, 2016, 17:56
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Quote:
Originally Posted by Lisandro Maders View Post
Yes, that's what I am doing. I was hoping there was someway of doing this in ParaView but actually is pretty much easier to do this with the openffoam utilities.

Anyway, cheers!
Hey,

if you use the openfoam utilities, why you are asking?
OpenFOAM have the ability that a lot of functions are already there (like the calculation of the gradient of the cell-center and boundary face-center).

I do not know if you can do this using paraview (maybe there is some workaround but I do not know it).
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Some interesting OpenFOAM tutorials, publications and videos on www.Holzmann-cfd.de
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Old   May 3, 2016, 17:58
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Actually, I was really making mess with this. Long day and I was tired. There is no reason for not using foam utilities, I just forgot everything I learned for some hours haha. But thanks anyway, I could be still struggling with this
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