where 



k = rate of energy dissipation coefficient (set equal 

 to 0.2 in RCPWAVE) 



/Ec \ = stable level of energy flux that the transformation 

 V B /s process seeks to attain 



The right-hand side of Equation 42 is simply a dissipation term. The sub- 

 script s is used to denote the stable level of some quantity. Substituting 



2 

 the linear wave theory estimate for E (E = 0.125 pgH ) into Equation 42 re- 

 sults in the following expression: 



9(H 2 c ) 



3X 



-w° 



(43) 



37. Various field (Thornton and Guza 1982) and laboratory (Horikawa 

 and Kuo 1966) experiments have shown that, well into the surf zone, the wave 

 height tends toward a stable value which is proportional to the local water 

 depth. This relationship can be expressed as 



H = Y h 



s ' 



where 



H = stable wave height 



Y = proportionality coefficient (set equal to 0.4 in RCPWAVE) 

 Equation 43 can now be rewritten as 



8x 



u 2 / 2, 2 

 He - ( y h c 



(45) 



38. This surf zone wave transformation model can be incorporated into 

 the conservation of wave energy equation (Equation 5) by simply adding the 

 dissipation term D to the right-hand side. The function D must now repre- 

 sent dissipation in the direction of wave propagation. Also for dimensional 

 consistency, the term D must be multiplied by the wave celerity and the mag- 

 nitude of the wave phase gradient, and the wave height must be replaced by the 

 wave amplitude function. In vector notation, the energy equation becomes 



a cc Vs 



a cc j Vs | - 



fz_\2 2. 2 



VS 



(46) 



22 



