FLOW SPEED (cm/sec) 



10 20 30 40 50 60 



DISTANCE (WIDTH) ALONG TANK (cm) 



70 





DEPTH 





—~- Z ■ 0.5cm 



- I— Z ■ 5.1cm 



-*- Z - 12.7cm 



-B- Z ■ 20.3cm 



-*- Z • 26.4cm 





Figure 12. Variation of flow speed with depth at test section B 



Streamer nozzles 



36. Streamer trap nozzle parameters investigated in the hydraulic tests 

 are illustrated in Figure 13: nozzle height and width (varied between 2 . 5 by 

 15 cm and 25 by 20 cm); presence or absence of a hood (extending from 2.5 to 

 5.1 cm forward of the element); presence or absence of a bottom lip (curved or 

 straight); and streamer length (varied between 0.36 and 2.0 m) . Dimensions of 

 the streamer trap nozzles were chosen to be large enough to collect a signi- 

 ficant (field measurable) quantity of sand during the testing period, yet 

 small enough such that a rack with a vertical array of streamers would be of a 

 size and weight that could be deployed during testing by one person. (See Part 

 II for a general description of the streamer trap.) Bottom lips were tested 

 on the lowermost streamers with the intention to streamline flow into the 

 streamer and decrease scour (tested during the sand-trapping phase). Other 

 components such as streamer mesh size (0.074, 0.105, and 0.149 mm) and a 

 plexiglass door designed to shut during reversals in flow (as occurs in on- 

 offshore sediment transport under oscillatory waves) were also evaluated. 



26 



