29 



similar results as a depth uniform current profile for the wave generated kinematics, 

 even at high order. It is expected that these results are applicable to irregular waves 

 as well, and thus the assumption of depth uniform current is reasonably appropriate. 



Another complication to be considered is the direction of any local current with 

 respect to the propagation direction of the waves. The U in Eq. 3.1 is the component 

 of the local current in the direction of wave propagation. In the case of a single 

 point measurement, no information is available to indicate the wave direction. Even 

 if the current magnitude and direction are known exactly, without an estimate for the 

 propagation direction of the waves, an accurate estimate for U is not available. Once 

 again, further information could be used to help resolve this difficulty. Knowledge 

 of the local bathymetry and the wave climate could provide this information. For 

 example, waves near a beach tend to propagate almost perpendicular to the shore, or 

 if there are directional measurements taken nearby available, they could be combined 

 with refraction computations to provide an estimate of the local propagation direction. 

 There must be some information available about both the local Eulerian current 

 and the local wave propagation direction in order to interpret accurately a point 

 measurement. 



The pressure records used for the examples in this chapter were generated either 

 analytically or in a laboratory flume. In both cases, the Eulerian current and wave 

 propagation direction are known. 



Spline of Record 



In order to avoid being restricted by the sampling rate of a particular set of 

 measurements, a continuous record is computed by spline interpolation among the 

 measured points. This allows the window widths and the number and location of 

 samples in each window to be chosen independently of the sampling frequency of the 

 data. Care must be taken, however, to be sure to include an adequate segment of 

 the record in each window. A window that includes only a single measured point is 

 computationally possible, but would result in misleading accuracy in the resultant 

 solution. 



