# Where can I find the theory for second order flap type wave generation?

I was wondering this since the Wiki only presents the formulation for shallow water piston type generation.

However, I am using flap type generation in my research and would be interested in the corresponding theory.

## Comments

@iarba27 can send some info

Hi,

the theory implemented is actually the same based on Liu and Frigaard (2001). What's changes is the transfer function and some coefficients that must be used to calculate the second- order correction. Further details are in chapter 7 of Hughes (1993), see:https://www.worldscientific.com/worldscibooks/10.1142/2154#t=aboutBook

Liu Z, Frigaard P.2001. Generation and Analysis of Random Waves. Laboratoriet for Hydraulik og Havnebygning, Instituttet for Vand, Jord og Miljoeteknik, Aalborg Universitet.

Thank a lot I will have a look.