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dissipation in terms of turbulent velocity fluctuations. These velocity fluctuations were assumed to decay exponentially with distance from the breakpoint. Dally, Dean, and Dalrymple (1985) quantitaively modelled wave transformation by including various wave parameters found subsequent to wave breaking. Their approach to quantifying the energy dissipation rate was to approximate it as the difference between the energy flux computed by linear theory and the energy flux associated with an empirically determined "stable" wave condition. Solving the energy and momentum equations numerically, the transformation of wave height was modeled. In making this model as realistic as possible, the effects of bottom friction, wave-induced setup, and beach profiles of arbitrary shape were included.
There has been much research in the field of cross shore current modeling. The basis for each model is similar in scope. They are based on the equations of mass, momentum, and energy conservation. An exception between any one model is how the return flow is represented. I A. Svendsen (1984b) used the qualitative ideas of Dyhr-Nielsen and Sorensen (1970) to quantitatively represent the mechanisms responsible for return flow. In his paper, he defined the driving force behind return flow as the local difference between the radiation stress and the set-up pressure gradient. Using Svendsen's (1984a) roller assumption for waves and particle velocities, an equation for the return flow was determined. In order to produce a steady state solution of the equation, turbulent shear stresses were required to balance out the inequality in the gradients of the radiation stress and the set-up. Boundary conditions consisted of satisfying continuity and using the Eulerian streaming condition at the bottom boundary layer to model the mean velocity. Svendsen found acceptable agreement between model and experimental data.
Stive and Wind (1986) continued work on cross shore modeling but modified Svendsen choices for the return flow boundary conditions. Both papers utilized the boundary condition that continuity had to be satisfied. The difference is in the second boundary condition. Svendsen