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  • Forced Convection - Numerical Results

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<iframe width="640" height="360" src="//www.youtube.com/embed/mv3uDy7ZuCY?rel=0" frameborder="0" allowfullscreen></iframe>

 

Nusselt No.

The following video shows you the procedure for calculating To calculate the Nusselt no. at x=2.67 m from the mixed mean and wall temperatures obtained above. To repeat the calculation at a different axial location, you can right-click on appropriate items in the tree, duplicate and modify as necessary.

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  • Export values from your Tw vs. x plot to an Excel file by clicking on the Export button, as previously discussed in the Wall Temperature Plot section. You'll see that the Excel worksheet contains many values of Tw vs. x.  
  • Then calculate Nu directly in the same worksheet from Tw and Tm. 

This yields a nice curve of Nu vs x.

Wall Shear

We plot the wall shear using the procedure shown in the video below.  

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<iframe width="640" height="360" src="//www.youtube.com/embed/WiK1uBTdK-M?rel=0" frameborder="0" allowfullscreen></iframe>

We then consider the trends in the wall shear in the heated, mixing and flow development sections and try to justify them through physical reasoning.

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<iframe width="640" height="360" src="//www.youtube.com/embed/NbdGrJTesZg?rel=0" frameborder="0" allowfullscreen></iframe>

You can spiff up your plot using the tips discussed below. This video also shows you how you could read in experimental results for comparing the wall shear between simulation and experiment.

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<iframe width="640" height="360" src="//www.youtube.com/embed/6RNykoM86xA?rel=0" frameborder="0" allowfullscreen></iframe>

When the simulation was repeated for conditions for which experimental data are available, we got the comparison shown below. The difference in the average wall shear in the heated section between the simulation and experiment is a respectable 4%. Note that the wall shear in turbulent flows is difficult to predict accurately due to the steep velocity gradients at the wall. 

 

 

Fanning Friction Factor

The Fanning friction factor, also called the skin friction coefficient, can be plotted using the procedure outlined below. 

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<iframe width="640" height="360" src="//www.youtube.com/embed/Jcht7CAPzAc?rel=0" frameborder="0" allowfullscreen></iframe>

 

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