Figure 1. Definition sketch for waves propagating on current

TR-02-22-RPT_2
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associated with it) implying that δ can vary from 180 to 180 deg. The

waves are assumed to always propagate towards the beach, which means that

90 <α <90 deg and that opposing currents are directed offshore and

following currents onshore.

Whether in a relative or absolute frame of reference, the wavelength L

should be the same. Thus, the relative wave period Tr and absolute period Ta

are given by:

Tr =

(3)

Ta =

(4)

Also, it may be noted that in a moving frame of reference, the relative phase

speed may be derived directly from the selected wave theory without a

current, yielding the following expression if linear wave theory is employed,

1/ 2

g



Cr =  tanh kd 

(5)

k



Chapter 3 Wave Model