Figure 6-10. Pneumatic bore generator. 



necessary for generation of the model tsunami. The pressure in the air 

 chamber above the raised water is then below atmospheric. To generate 

 the wave, the water in the tank is discharged by allowing air to enter 

 the chamber through several ports, the areas of which may be varied as 

 required by removable circular-orifice plates. Each port is fitted with 

 valves actuated by microswitches to control the rate of air entering the 

 pneumatic chamber by programing a sequence of opening and closing each 

 port. This results in a variation of the port area as a function of 

 time so that, with proper calibration, reproduction of the selected bore 

 height, shape, and duration of overtopping of the test structure can be 

 obtained. Design of the tank height and length with enough head and 

 water volume available to generate the maximum wave can be accomplished 

 by the equations derived by Keulegan (1966) , 



d Vd VV 4d/l+f 



Mf) 



2k -HMll/i 



^2-d(h;;r^ 



^^^2 _ (gd)l/2 / 1 H\ 

 kj (l+f)C\^ 2d/ 



^ = l-ki-2k2t; and ^p = kj 



(6-27) 

 (6-28) 



(6-29) 

 (6-30) 



353 



