Sxx 



Syy 



I Y t t 



I Syx 



Sxy 

 Sxy \ 

 Syx. 



Wave C 

 Bottom Contour 



rest ft t t 



Sxx 



Syy 



+x 



Shoreline 



Figure 19. Definitions and nomenclature for radiation stress components. 



where the overbar indicates a time-averaged mean. For convenience in further 



evaluation, S.^^. is rearranged and divided into three parts as follows: 

 xx 



XX 



pu^dz + 



(p-p )dz + 



pdz 



(2) 



-d 



-d 



^XX ^xx ^xx ^xx 



(3) 



,(1) 



The assumptions now begin. In the first term S „ , the integration above the 

 Stillwater level to z = n produces a third-order term (proportional to a^) and 

 is neglected. S^}.^ is generally positive and can be considered a Reynolds 

 stress integrated from the bottom to the Stillwater level. 



,(1) 



'xx 



pu'^dz 



(4) 



-d 



67 



