15 Minnie Time Trace of Pressure (2 Hz) 



File #A0G08 



Broad Banded Random Wave 



Figure 9-12. Time-trace-interpreted pressure data 



The velocity time traces in Figure 9-11 and Figures 122-196 show that the 

 monochromatic waves (A1317A and A0817A) do indeed show equal velocities 

 with each passing wave, and unequal onshore and offshore excursions of the 

 amplitudes past zero suggest that the waves are not first-order linear. The 

 narrow-band random waves (A0510A and A0711A) show definite wave 

 groups of differing periods along the 15-min intervals. The broad-band 

 random waves (A0608A, A0611A, A0812A, and A0814A) show some periods 

 where groups of waves seem to occur, but these events are not as regularly 

 occurring or as easy to identify as those for the narrow-band waves. 



The pressure data, Figure 9-12 and Figures 197-1103, show the same trends 

 as the velocity data for each type of wave even more clearly. They show that 

 even the broad-band waves have a "groupiness" where some groups have 

 longer periods than others. Average pressure data shows that the center of the 

 instrument mounting was about 125 cm below the still-water level of the 

 channel. 



Chapter 9 The Ohio State University Measurements 



179 



