Wave resistance: transverse wave cut
 

Hi! I've new in this forum and I really hope you can help me about a problem! Well, I try to calculate the wave resistance throught sperimental method named "transverse wave cut" done by Eggers and Sharma (you can find some info at "http://www.iwwwfb.org/Abstracts/iwwwfb13/iwwwfb13_34.pdf").
My problem is the application of the expression, because I don't understand what I have to put into it!!! I tried to do the dimostration and its perfect, but I don't understand how I can use it. What do I replace to the F(u), G(u), u, s? The only things that I have are the waves' elevation got from a simulation with OpenFoam!
I thank anyone answer me
greets
Luca