5- Dye Injection. 
Longshore current velocities for tests 5 to 15 were measured by injecting 
dye into the surf zone through a hose which ran from the sand feeder to a 
small stake in the surf zone. Dye was poured by hand into the top of the 
hose. Table 2 gives the locations of the dye injection by test numbers. The 
change in location of the stake in tests 7 to 10 was a procedural error and 
not planned for a special purposee The dye injection procedure is discussed 
in detail in the next section. 
Table 2. Locations of dye injection by test number. 
Test Nos. | Dye injected Dye timed Dye timed | Timed distance 
at range from range traveled 
(m) 
Bistand 6 | 
7 EO INO) 
ll to 15 
6. Sand Size. 
Figure 13 shows the size distribution of the sand used for all 15 tests. 
The median diameter was 0.22 millimeter. The geometric standard deviation is 
defined as 
d 1/2 
“3 aa (20) 
where djg and dg, are the sand sizes at which 16 and 84 percent, respec— 
tively, of the sample is coarser. The value of for the sand used was 
1.22. Figure 13 indicates that the sand was well ore 
Screen Opening (mm) 
0.1 
0.0! 0.050102 05 § 2 5 10 30 40 50 60 70 00 ie 95 : 99 99.0 99.9 
miert Coorser 
Figure 13. Size distribution of sand used for all tests. 
25 
