UNIFORM 

 ^FLOW 



Figure 36. Sketch for discussing the hypothetical disequilibrium of sand 

 flux due to length of test section 



measurement has been rejected. In considering all possible reasons for the 

 discrepancy between sand fluxes obtained with the basin sampler and C nozzle, 

 it has been decided that the likeliest source of the incongruity is the pit 

 sampler. In the following, sand- trapping efficiencies for the SUPERDUCK and 

 DUCK85 nozzles have been calculated using the C nozzle flux equal to the 

 ambient sand transport flux. 



Sand-Trapping Efficiency Results 



102. Tests conducted with midflow speeds greater than 60 cm/sec 

 resulted in a flat-bed sand transport condition, which is most like the mode 

 of transport occurring in the surf zone. Lower midflow speeds resulted in 

 well -developed migrating ripples, which are not characteristic of the surf 

 zone. All nozzles were fully tested in the 60 to 66 cm/sec range of midflow 

 speeds. Therefore, for the purpose of determining nozzle sand- trapping 

 efficiency, equations were developed to describe nozzle flux for the 60 to 

 66 cm/sec range of midflow speeds as follows: 



74 



