The average wave height in each tank was determined by averaging the 

 average o£ the last 10 waves in the last 20-second interval for each o£ 

 the 10 minutes. The average wave height was 0.36 foot (11.0 centimeters) 

 in both the fixed- and movable-bed tanks. The equal values are coin- 

 cidental, since the gages were different distances from the profile. 



Table 5 shows the average incident wave heights in the two tanks. 

 These heights were determined by the automated method for determining the 

 reflection coefficient, K^ (see Vol. I). The range of values for the 

 fixed-bed tank was 0.03 foot (0.9 centimeter). This variation is prob- 

 ably caused by generator operation variation, measurement errors, and all 

 errors not caused by a changing profile. The range of values in the 

 movable-bed tank was 0.08 foot (2.4 centimeters). The difference between 

 the two amounts of variation indicates that 0.05-foot (1.5 centimeters) 

 variation in the movable-bed tank was due to the changing shape and 

 position of the profile, causing a varying profile reflection and thus a 

 varying re-reflection from the wave generator. The re-reflected wave 

 superposing with the generated wave created an incident wave height which 

 varied in time. 



Table 5. 



Incident wave heights, movable- 

 and fixed-bed tanks. 



Time 



Incident wave 



height (ft) 



(hr) 



Movable bed 



Fixed bed 



0.66 



0.39 



0.38 



1.50 



0.40 



0.38 



3.00 



0.36 



0.38 



5.00 



0.36 



0.39 



10.00 



0.38 



0.40 



20.00 



0.37 



0.38 



25.00 



0.38 



0.39 



30.00 



0.37 



0.37 



35.00 



0.34 



0.39 



45.00 



0.36 



0.40 



80.00 



0.41 



0.40 



105.00 



0.40 



0.38 



110.00 



0.39 



0.37 



120.00 



0.40 



0.38 



125.00 



0.36 



0.38 



130.00 



0.36 



0.39 



140.00 



0.41 



0.37 



150,00 



0.39 



0.37 



155.00 



0.41 



0.38 



160.00 



0.40 



0.39 



165.00 



0.41 



0.38 



170.00 



0.39 



0.38 



180.00 



0.42 



0.39 



Avg 



0.39 



0.38 



