Van Mater and Neal 



location and the second wave did not break until a subsequent station, 

 A different source model giving a later peak to the first envelope 

 would probably also correct this discrepancy. The theory predicts 

 about the right number of waves breaking at subsequent stations, 

 although there Is disagreement In some cases on which Individual 

 waves break. The decay rate after breaking appears to be about right 

 for the envelope heights In the surf zone match quite well. As before 

 there Is still distortion of the envelope due to backwash effects. The 

 stability criteria seems to give a surf zone of about the right length, 

 but the data are Inadequate to say conclusively. Comparison with a 

 much larger number of experiments Is needed to fine tune these 

 empirical breaking relationships; however Impulsively- gene rated 

 wave system furnish an Ideal vehicle for such studies, 



(I) The form of the breaking waves and the near-breaking waves Is 

 very poorly predicted by this program. The wave slope asymmetries 

 which develop near and at breaking are not reflected at all In the 

 cnoldal wave form. For future generations of the program the 

 Incorporation of a theory developed by Biesel [ 1952] Is under con- 

 sideration, 



(j) Despite the fact that the "correction factor" approach In account- 

 ing for wave peak- up Is somewhat distasteful It appears useful at this 

 evolutionary stage. At the minimum the peak-up correction factor 

 should be refined to reflect the Influence of co, H/h, and bottom 

 slope. Clearly what Is needed Is a computationally useable non-linear 

 theory which predicts this phenomena, 



(k) No comments can be miade on the quality of predictions along the 

 refracted rays. Such data were taken In the WES experiments but 

 are not presently available for comparison. 



In summary it may be said that for small and moderate size 

 explosions the theoretical and empirical program presented gives 

 good predictions of envelope shapes ajtid asymmetry, wave form, 

 and times of arrival of wave groups In shallow water. Wave height 

 enhancement In very shallow water and viscous attenuation are some- 

 what under-predicted. The quality of the prediction of the phase of 

 Individual waves remains to be established. For large explosions 

 the present source model gives only a fair prediction of envelope 

 shape. Group times of arrival and form of non-breaking waves con- 

 tinues to be well predicted. Form of near-breaking waves Is poorly 

 predicted. Counterflow currents have a prominent Influence when 

 waves are very large, but the presence or effect of such currents is 

 not predicted. The location, size, and extent of the surf zone appears 

 satisfactory based on a llnnlted comparison. 



260 



