4 6 8 I0" 2 2 4 6 8 I0" 1 

 Unit Discharge q of Free Air (ft 3 /s/ft) 



Figure 139. Effect of unit air discharge, q, and relative depth of submer- 

 gence, y/d, on maximum surface current velocity, U (after 

 Straub, Bowers, and Tarapore, 1959). 



Straub, Bowers, and Tarapore (1959) determined that the power required 

 for discharging air through the pneumatic breakwater could be conveniently 

 expressed by the dimensionless parameter 



(hp/ft) 



(Pg 



3/2 t 5/ 2 



The horsepower per foot was computed at the orifices from the expression: 



(qyd x ) 



where 



q 



Y 

 d 



hp/ft = 



= unit air discharge at orifice 

 specific weight of water 

 submergence of orifices 

 density of water 

 acceleration of gravity 

 wavelength 



550 



(76) 



(77) 



201 



