82 



Generation, Growth and Propagation of Waves 



W d 



c d 



QW2)l ' 



(IV. 24) 



it was for the four models 00085, 0024, 00028 and 0195 respectively. 



The experiences made by Motzfeld prove that the distribution of pressure 



on the water surface becomes unsymmetrical through the influence of friction. 



g 



Fig. 40. Streamlines of the air motion over the wave-shaped surface and the total pressure 

 on the streamlines. Wave with a trochoid profile with A = 150 mm and 2 A = 145 mm. 



rrr-~~T. 



Fig. 41. The same as in Fig. 40. Wave with sharp crest (crest angle 120°) with X = 150 mm 

 and 2A = 20 mm (according to Motzfeld, 1937). 



Consequently, in case the wind velocity exceeds the wave velocity, the wind 

 must add work to each wave crest and the wave constantly receives energy 

 from the wind. Concerning the wind field above ocean waves, see especially 

 Roll (1948). 



