. 1 



0.0036 



- 



1 1 1 1 1 



LEGEND 



- 





0.0032 



- 



______ r;pppjp/\, pipi^lpRA^ypp 



- 





DESIRED SPECTRA 



^ 0.0028 



- 



1 



- 





~ 0.0024 

 2 0.0020 



LU 



Q 



- 



1 







< 0.0016 



> 



y 0.0012 



- 



1 



— 





CO 





1 |k 







0.0008 



- 



/ \ ii 



- 





0.0004 



- 



J ^V^ 



- 





0.0 





S , 1^"*^^ 



A* 









0.4 0.8 1.2 1.6 2.0 



2.4 





FREQUENCY (Hz) 





Figure 1 9. Typical energy density versus frequency plots (model terms) for a 

 wave spectra; 7.9-sec, 2.07-m (6.8-ft) waves (prototype) 



200. 250. 300. 



Time (sec) 



Figure 20. Typical model-scale wave train time series; 7.9-sec, 2.07-m (6.8-ft) waves (prototype) 



then were adjusted by application of Keulegan's equation^ to compensate for 

 excessive model wave height attenuation because of viscous bottom friction. 

 From this equation, reduction of model wave heights (relative to the prototype) 

 can be calculated as a function of water depth, width of wave front, wave period. 



Keulegan, G. H. (1950). "The Gradual Damping of a Progressive Oscillatory Wave with 

 Distance in a Prismatic Rectangular Channel," Unpublished data. National Bureau of Standards, 

 Washington, DC, prepared at request of Director, WES, Vicksburg, MS, by Letter of 2 May 1950. 



40 



Chapter 6 Physical Model 



