Write an appropriate dimensionless correlation for the average Nusselt number for these data and state any limitations to your equation.
Suppose that the graph below shows measured values of hc for air in forced convection over a cylinder of diameter D plotted on a logarithmic graph of NuD as a function of ReDPr.
GIVEN
Forced convection of air over a cylinder
Experimental data given above
FIND
An appropriate dimensionless correlation for the average Nusselt number
The data lies along an approximately straight line on the log-log graph. Therefore, a straight line fit
will be used. Choosing two points on the graph
A straight line on the log-log plot is represented by
Substituting the two points into the equation and solving for a and b
Therefore
or
This is based on data in the range 1 < Red Pr < 103 and is therefore valid only in this range.
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