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Thermal_engg August 6, 2013 00:46

Nusselt number calculation
Hello everyone,
I am modelling a rectangular natural circulation loop with isothermal heat source and heat sink and the rest of the surfaces adiabatic.This whole system is isolated from the surroundings.
I am using carbon dioxide as a fluid and employing piecewise linear model in the subcritical region of CO2.
and have specified uniform wall thickness throughout and enabled the "Shell Conduction" option.

I wanted to calculate Nusselt number in the different sections of the geometry like the heating/cooling section.But the default option "Surface Nusselt number" is giving absurd values.

I also tried doing it manually where first I created a surface at a specified coordinate;calculated bulk mean temperature and found surface heat flux and area weighted average of 'k'.After that just plugged the values in the formula for Nusselt no. and got a satisfactory value.

BUT this whole process is tedious for just ONE Nusselt no.
Is there any way to calculate it quickly? Thnx

vasava August 7, 2013 03:26

Have you considered writing a UDF or data sampling?

Thermal_engg August 7, 2013 04:01


Originally Posted by vasava (Post 444280)
Have you considered writing a UDF or data sampling?

I don't know either of those .Could you please provide me with suitable links to these methods.Thnx

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