SECOND ORDER WAVE FORCE EFFECTS ON A SEMI- SUBMERSIBLE PLATFORM

Wave making forces are one of the important design criteria for offshore platforms. Linear or first order wave forces are well explained and offshore platforms are designed such that its natural frequencies of motion are well outside the first order excitation wave forces. But the effects of Nonlinear or second order wave forces are sometimes neglected since its magnitudes are less compared to first order ones. But the low frequency components of second order wave forces can cause slow drift motions of the platform, causing resonant motions of the platform. This work shows the numerical evaluation of second order wave force and its effects.