To aid in the use of this theory for analysis, prediction, and calibra- 

 tion purposes, Kraus and Sasaki (1979) prepared the results shown in Figure 

 30. Here, Vj^^^^ is a maximum velocity located at position Xjj^^^j ^b ^^^ 

 breaker velocity, Vi^ the midsurf velocity, and V a mean or average velocity 

 across the surf zone. All are dimensionless and y is taken as unity. For a 

 fixed P*, the location of V is seen to move slightly shoreward as a^^ in- 

 creases. 



Figure 30. Calculated quantities as a function of mixing parameter P* 

 and breaker wave angle (from Kraus and Sasaki, 1979). 



All dimensionless velocities decrease as P* increases except V;^ at the mid- 

 surf position. In fact, Vp is relatively insensitive to wide variations in 

 P* and displays less variation to change in breaker angle than V^ or Vj^^^^. 

 On the other hand, V^j^^^ displays the largest spread with a^ and greatest 

 variation with P*. For this reason, Vjj^^^ and \ig^-^ have been used by Kraus 

 and Sasaki (1979) to fit and compare theory with observation as discussed in 

 detail in Chapter 4. 



e. Paramet e r Studies . In either_the original or modified theories, the 

 longshore current velocity at a g iven x depends upon six independent variables: 



Y, tang, C, 



-h'S 



at a g : 

 (or C, = vghT) , and N or T. The reference velocity v* 



varies with the first four plus C, = (gh, )*S to give the scale. The dimensionless 



106 



