Can anyone help me to calculate nusselt number in a circular tube with constant wall temperature using Comsol step by step?
I do not intend to use correlations. (I want to calculate Nu using its definition))
It is obvious that I need to find h=q/(Ts-Tm), and Then Nu=hD/k.
q= heat flux
Ts=wall temperature
Tm=bulk temperature
D=tube diameter
k=thermal conductivity
However, Ive tried many times, and the results do not match previous works.
Does anyone have any experience calculating Nu number in comsol?
I would be thankful if anyone can help.
you can define equation like the equation that Dr. Khaled Al-Farhany presented ( Nu= ht.gradTx*nx+ht.gradTy*ny+ht.gradTz*nz) ) in comsol global definitions>parameters and calculate this parameter like other parameters
Nusselt No is a functiuon of Gr and Pr for free convection, while it is function of Re and Pr for forced convection. There are constriants like constnat heat flux, constnat wall temperature etc,. Complexity will be increased, if corelations are not used, among these dimensionless numbers. iF this is free convection, you have to calculate buoyant foce, inertia force, viscous force, and you should know the properties of fluid at film temperature like speciic heat, dynamic visocity and thermal conductivity.
Thank you for your answer dear Maddali V S Murali Krishna
I forgot to use film temperature for fluid properties. This might help.
Thank you so much Absul aziz Jafaar
I've done the simulation already, and I have the results at the moment. However, I do not know how to process these results (step by step) to find Nu. I do know how to calculate it theoretically but I do not know what makes this error in my calculations.
you can define equation like the equation that Dr. Khaled Al-Farhany presented ( Nu= ht.gradTx*nx+ht.gradTy*ny+ht.gradTz*nz) ) in comsol global definitions>parameters and calculate this parameter like other parameters
Khaled Al-Farhany please sir inform me how to calculate the local Nusselt number.... Nu= ht.gradTx*nx+ht.gradTy*ny+ht.gradTz*nz) is use for calculate the average nusselt number.....thanks
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