Non-normal descriptions of morison-type wave forces
Date of Original Version
The usual description of the force exerted by a stochastic wave is extended to include the non-normality of that force. In particular, the Morison equation is used to describe the force resulting from a sea state with stationary, normally distributed water velocities. Thus, the force non-normality which is considered results only from the nonlinearity of the Morison equation. The fourth order cumulant function is used to describe the non-normality of the force. The same information is also represented as a three-dimensional spectral density, which results from a three-fold Fourier transform of the cumulant function. Closed form solutions are not found, but the results of a power series expansion method appear to give good approximations. Potential applications of the results involve determinations of the non-normality of the response of a structure subjected to a Morison-type wave force. Such response non-normality can then be used to substantially improve estimates of structural failure, due to either first passage or accumulation of fatigue damage. © ASCE.
Journal of Engineering Mechanics
Hu, Sau-Lon J., and Loren D. Lutes. "Non-normal descriptions of morison-type wave forces." Journal of Engineering Mechanics 113, 2 (1987): 169-209. doi:10.1061/(ASCE)0733-9399(1987)113:2(196).