Numerical study of wave and longshore current interaction
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Numerical study of wave and longshore current interaction TANG Jun1∗ , SHEN Yongming1 , SHI Feng1 , ZHANG Ming1 1
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China
Received 10 June 2011; accepted 20 September 2011 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2012
Abstract Wave and longshore current interaction was examined based on the numerical models. In these models, water waves in the presence of longshore currents were modeled by parabolic mild slope equation, and wave breaking induced longshore currents were modeled by shallow water equation. Water wave provided the radiation stress gradients to drive current. Wave and longshore current interactions were considered by cycling the wave and longshore current models to a steady state. The experiments for regular and irregular breaking wave induced longshore currents by Hamilton and Ebersole (2001) and Reniers and Battjes (1997) were simulated. The numerical results indicate that the present models are effective for simulating the interaction of wave and breaking wave induced longshore currents, and the numerically simulated longshore current at wave breaking point considering wave and longshore current interaction show some disagreement with those neglecting the wave-current interaction, and the breaking wave induced longshore current effect on wave transformation is not obvious. Key words: water wave, longshore current, wave current interaction, numerical simulation, surf zone
ation stresses. Goda (2006) studied the influence of several factors on the longshore current induced by random breaking waves. The interaction of coastal water waves and breaking wave induced nearshore currents, especially longshore currents, is one of the classic and popular topics in coastal research fields. The effect of currents on shallow water waves was studied by several researchers, and it is shown that the wave transformation due to current is obvious. The currents effect on the wave transformation is always substantial if they are strong, and they create a doppler shift and cause wave refraction, reflection, and breaking, which can result in overall redistribution of the wave energy. Yu and Slinn (2003) studied the effects of wave and rip current interaction, and indicated that the rip current effect on wave is obvious as it shifted the wave energy distributions. This paper aimed to study the interaction effect of wave and longshore current based on numerical simulations. The numerical models consisted of surface water wave and wave breaking induced current
1 Introduction Surface water wave induced longshore currents are likely present on most beaches as a component of the complex pattern of nearshore circulation. Surface water waves propagating from deep ocean to coastal zone undergo obvious transformation in shallow coastal areas as a consequence of bathymetric variations and domain geometry. When surface waves break on beaches, wave energy is lost to turbulence generated in the process of b
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