Test n -4 (Galvin) 

 H^ = 0.13ft. 

 Y • 0.954 

 a = 3.5" 

 T = l.25sec. 

 r ' 0.0033ft. 

 "f„b= 0.023 



V ((ps) 



measured 

 ttieoretlcal 



Figure 60. Thornton's longshore current profile theory versus laboratory 

 data of Galvin and Eagleson, 1965, test II-4 (after Horikawa, 

 1978). 



coefficient (vl) and bed friction coefficient (f^^) employed in his theoretical 

 analysis. Only bottom roughness (here r = 0.0033 foot for a concrete beach) 

 is chosen in Thornton's model. Comparisons for two other cases with larger 

 waves at greater angles are shown in Figure 61. In all cases, the theory 

 predicts too strong a current outside the breaker line. Some field data 

 by Ingle (1966) taken at Trancas Beach, California, are used to compare 

 the theory as shown in Figure 62. The beach profile was represented by 

 a fourth degree polynomial. The magnitude of the eddy viscosity is much 

 larger in the field than in the laboratory but values employed are too 

 large and overly smooth the profile. 



174 



