Impulsively Generated Waves Propagating into Shallow Water 



Predictions are displayed for the five stations, 59, 64, 71, 76, 100 

 shown in Fig. 1. The first station, station 59* maybe considered 

 to be in the transition range from deep to shallow water for the larger 

 waves in these explosions. The remaining stations are all in progres- 

 sively shallower water. A frequency range was chosen which would 

 permit the computation of the first four wave groups. The full four 

 groups are shown at station 59, Fig. 6; however since only the first 

 two groups are of practical interest these are the only ones shown 

 in the remaining displays. 



Wave breaking occurred for the large explosion but not for 

 the two smaller explosions. The individual phase waves which have 

 either just started to break or are continuing to break are indicated 

 by an asterisk in Fig. 11, The irregular shape of the envelope at 

 stations 71, 76, and 100 is caused by the fact that breaking and wave 

 (envelope) height decay after breaking have already occurred for these 

 frequencies within the envelope. Typically, breaking will start within 

 a small frequency band then spread to adjacent frequencies as the 

 envelope moves inshore. 



The effect of refraction is shown in Fig, 8 for the moderate 

 explosion case only. The wave trains correspond to those along the 

 ray families Gq* = 0°, 20°, and 40°. Mean offsets of the path from 

 the axis are indicated. Three stations, 59, 76, and 100 are shown to 

 give a representative effect. 



v::-^-AjOJLflLA-A^ . , roW\. - -' - - 



JCXIJXIJ^ . r > A AA /^ - 



- fi~cO-LLteA> ^ ^iazma- 



smTioN lao 



g- A JC/UUUlJVA - »v AAA^ 







^^^^Pk NSA^ - ^iv^ 



STATION a^ 



20 30 



90 60 70 eo 



lime — — t-v/sTfir 



00 100 



Fig. 8. Prediction of wave system along refracted rays for 

 moderate explosion 



257 



