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-   -   Nusselt Number problem (https://www.cfd-online.com/Forums/openfoam-solving/97935-nusselt-number-problem.html)

Goutam February 28, 2012 14:33

Nusselt Number problem
 
(buoyantBousseinsqSimpleFoam)

I want to calculate local and average Nusselt number for a square cavity when
T_left=303 K, T_right= 283 K, T_ref= 293 K, Detta T = 20, u=v=0 for all wall and uper and lower wall are adiabetic.

local Nu = -0.05 * Grad(T) at the wall

average Nu = Integration [local Nu, {y, 0, 1}]

How I will calculate this, please help me?

I am considering the benchmark problem, paper name:

Natural convection flow in a square cavity revisited: laminar and turbulent models with wall functions, International journal for numerical methods in fluids, vol. 18, pp. 695-719, 1994.

Goutam March 3, 2012 09:34

I have calculated the local one.

ternik July 3, 2012 09:10

For obtaining the "average" Nusselt number use the numerical integration (Simpson's 1/3 method)!

What version of Open Foam have you used for your calculation?

Best,
Primoz

Goutam July 5, 2012 12:10

Quote:

Originally Posted by ternik (Post 369521)
For obtaining the "average" Nusselt number use the numerical integration (Simpson's 1/3 method)!

What version of Open Foam have you used for your calculation?

Best,
Primoz

I have calculated both the local and average Nu. I am using OF 2.1.0.

ternik July 5, 2012 15:21

Quote:

Originally Posted by Goutam (Post 369955)
I have calculated both the local and average Nu. I am using OF 2.1.0.

Nice! I hope your results are in agreement with the benchmark!

By the way, what Ra and Pr have you studied (modelled)? Because I have quite some problems with the Rayleigh-Benard convection (laminar natural convection in a square cavity heated from bellow) for Pr=10 and Ra=1e05; I am using buoyantBoussinesqSimpleFoam (Open Foam 2.1.1) and results are "not good" (maybe you can check my post http://www.cfd-online.com/Forums/ope...implefoam.html )

Is there a chance that you send me your case files?

Best,
primoz

ternik July 12, 2012 05:14

Quote:

Originally Posted by Goutam (Post 369955)
I have calculated both the local and average Nu. I am using OF 2.1.0.

Dear Goutam,

I would realy appreciate if you could send me your natural convection case (i.e. files)!

I still have some problems with the Rayleigh-Benard convection (laminar natural convection in a square cavity heated from bellow) for Pr=10 and Ra=1e05; I am using buoyantBoussinesqSimpleFoam (Open Foam 2.1.1) and results are "not good".

Best,
Primoz


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