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1. For Pr=1 (Air Cp of 1440.9 j/Kg-k), go to the csv file exported from CFD Post and read off the Nusselt number value for Re = 40,000 (this process is shown in the Nusselt Number Variation video above). This is the Nusselt number for Pr=1 at that Reynolds number.  

2. Change Air Cp in Fluent under Setup>Materials>Fluid>Air (To get a Pr=2, you need to double the Cp value for air)

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3. Run more iterations until the you get convergence (when the residuals are below 1e-6). Note you don't need to reinitialize the guess values since the velocity and pressure fields remain the same. Cp affects only the energy equation. 

4. Export Nux vs. Rex to a csv file. Read off the Nux value for Rex = 40,000. This is the Nux value for the new Prandtl numberPr. 

5. Create a list of values in Excel from these runs with the following three columns (you are only changing the Pr number through the Cp of air enough times to notice a trend, 3 data points are not enough to notice a trend but 20 data points might not be the most efficient use of time)

        Cp      Pr     Nux

6. Plot Nux vs Pr and add the trend line to get a fit and the exponent m

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