The eddy viscosity model in Jonsson, Skovgaard, and Jacobsen (1974) 

 was improved by Skovgaard, Jonsson, and Olsen (1978). Different models 

 and lateral mixing coefficients were employed within and outside the breaker 

 line. An example of the result is shown in Figure 64 for two different 

 cases of lateral mixing. Both show much smaller tails beyond the breaker 

 zone which is closer to reality where "... observations indicate a vir- 

 tually complete absence of turbulent mixing outside the breaker zone" 

 (Battjes, 1978). The experimental data are again from Galvin and Eagleson 

 (1965). The tail was found to diminish further as bed slope decreased. 



I Galvin ond Eagleson (1965), Ser.III Test No. 3 



r 1/^.= 0.220 s^' ;9^' Ixgl'V^h in SZ 

 |_i'T = !^5l% alcos^Q) in NBZ 



V(m/s) 



--[ 



1/t = 0.177 s''' /Q^'^Mx^lVgh in SZ 

 /sohaVe in NBZ 



Figure 64. Skovgaard, Jonsson, and Olsen 's longshore current profile versus 

 laboratory data (after Skovgaard, Jonsson, and Olsen, 1978). 



The most recent longshore current profile model by Kraus and Sasaki 

 (1979) was verified with new laboratory and field measurements taken in 

 Japan. The theory is discussed in complete detail in Chapter 3 and essen- 

 tially extends the weak current large-angle theory to include lateral mix- 

 ing stresses. A key dimensionless parameter in the theory is P* which 

 indicates the relative importance of the lateral mixing stress to the bed 

 stress and also includes wave setup effects. Laboratory measurements of 



178 



