NUMERICAL STUDY OF LOW FREQUENCY SURF ZONE MOTIONS

H. Tuba Ozkan-Haller, James T. Kirby

Abstract


This paper describes the application of a model of the two dimensional shallow water equations to the growth of instabilities of the longshore current at SUPERDUCK on October 18th. Simulations are carried out using two initial current profiles. In the first case the initial longshore current profile results from a balance between bottom friction, the radiation stress gradient and lateral mixing due to turbulence. In the second case lateral mixing is neglected. The shear wave climates resulting from both simulations are analyzed and compared to data. In the first case the energy in the shear wave band is underpredicted whereas in the second case, it is overpredicted. In both cases, the initial longshore current profile changes due to lateral mixing induced by the shear instabilities. The resulting longshore current profile after shear instabilities have reached finite amplitude is found to be very similar for both cases.

Keywords


surf zone; numerical study; low frequency motion

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