I would like to determine the pressure drop of fluid in cross flow over a bank of tubes. (see figure 1).
Previously, I've used the correlation listed in "Fundamentals of Heat and Mass Transfer" by Incopera and DeWitt. However, this correlation requires looking up coefficients on a graph (see figure 2 - f is used to mean Eu/k by Incopera).
Now, I'd like calculate a pressure drops across a large number of tube banks in a computer program I'm running, so I need a correlation that's either just one equation or based on a lookup table. I tried using tables 1 and 2 from the Thermopedia article on tube banks in crossflow. While this gives reasonable answers at some points, it also produces clearly incorrect answers at others. For example, for a square in-line bank, this correlation shows that Euler's number for b=2.0 exceeds Euler's number for b=1.5 as Re approaches 1e6, which doesn't line up with the graphs and also is obviously an incorrect answer (See figure 3, b=1.5 is in orange and b=2.0 is in green).
Is there a correlation which I could use in my program which is more accurate than the one on Thermopedia?