Morison equation

The Morison equation gives the in-line force per unit length on a slender cylinder in oscillatory flow as an inertia term plus a drag term: f = C_m times rho times (pi D squared over 4) times u-dot plus one-half C_d times rho times D times u times the modulus of u, where D is diameter, u and u-dot the wave velocity and acceleration, rho the density, C_m the inertia coefficient (C_m = 1 + C_a), and C_d the drag coefficient. It applies when the member is slender (D over L below about 0.2, so diffraction is negligible), with C_m and C_d set by Reynolds and Keulegan-Carpenter numbers. It is the standard load model for jackets and monopiles.