STATISTICAL PROPERTIES OF WAVE FORCE

Expressions of the mean and standard deviation of wave force on vertical cylinder in a random field are derived. Wave force is evaluated according to Morison's formula and the sea surface is assumed to be Gaussian. The effects of free surface fluctuation, which have previously been overlooked, are included. The mean and standard deviation are computed and results are presented graphically. It is shown that the mean of wave force is nonzero, contrary to past results. Also, the standard deviation of wave force deviates drastically from that when the free surface fluctuation phenomenon is ignored especially in the vicinity of the mean water level. Since most of the water movements are around and above the mean water level where the foregoing observed discrepancy is most pronounced, it is concluded that the effects of the free surface fluctuation phenomenon on wave force has important implications on the design considerations of marine structures that protrude above the mean water level.