EFFECT OF NONLINEAR WAVE-CURRENT INTERACTION ON FLOW-FIELDS AND HYDRODYNAMIC-FORCES

A fifth-order theory for solving the problem of interaction between St okes waves and exponential profile currents is proposed. The calculate d flow fields are compared with measurements. Then the errors caused b y the linear superposition method and approximate theory are discussed . It is found that the total wave-current field consists of pure wave, pure current and interaction components. The shear current not only d irectly changes the flow field, but also indirectly does sx, by changi ng the wave parameters due to wave-current interaction. The present th eory can predict the wave kinematics on shear currents satisfactorily. The linear superposition method may give rise to more than 40% loadin g error in extreme conditions. When the apparent wave period is used a nd the Wheeler stretching method is adopted to extrapolate the current , application of the approximate theory is the best.