Author(s): E. M. Valentine; C. G. Dinsley
Linked Author(s):
Keywords: Hydraulics; Sediment transport; Longshore current; Radiation stress
Abstract: This paper concerns the concept of radiation stress and its application to a local bathymetry wherein there are longshore variations in depth. Radiation stress, first introduced by Longuet-Higgins & Stewart (1960), is defined as the excess flux of momentum due to the presence of surface waves. This concept drives longshore sediment transport and is represented by an important term in the momentum equations that must be solved to calculate the longshore current. Local variations in longshore sediment transport can lead to sediment accretion/erosion and a variation in depth in the longshore direction. The effect of a gentle slope in the longshore direction upon the formulation of the radiation stress is examined. The momentum flux for still water with such a bed slope is found to be the mean of the flux at the maximum and minimum depth and a tertiary variable point, whose position is also investigated. After the manner of Longuet-Higgins & Stewart (1964), a progressive wave is then added to obtain the radiation stress. The new formula is found to agree with the classical formula a the bed slope approaches zero. Finally, the effect on the radiation stress magnitude of varying bed slopes is investigated.
Year: 2003