190
5 Wave Evolution in Non-uniform Currents in Deep Water
Fig. 5.16. Change of wave heights and lengths in countercurrent taking into account reverse waves with n = 5, 'Y = 0.67 and different values of initial wave
steepness: 1 - 0. 75 X 10- 3 ; 2 - 7.52 X 10- 3 ; 3 - 20.8 X 10- 3 ; 4 - 40.6 X 10- 3 ;
5 - 62.7 x 10- 3 ; 6 - 200.3 x 10- 3 . Solid lines denote mean wave heights h/ho and
dotted lines wavelengths 'Y / "(o
the mean wavelength decreases with increasing parameter value and then it
starts increasing. The least wavelength is observed for waves with small initial
steepness. This occurs due to the presence of reverse waves, whose influence
is greatest at small values of the initial wave steepness 8.
5.6 Wave Diffraction Around a Caustic
Wave height evaluation in the vicinity of the caustic. As shown in
the previous section, as soon as the spectrum becomes narrowed, the maximum wave height tends to a larger value in the countercurrent. It becomes
infinitely large at the point v ~ 0.25 in the limit n -t oo (see Fig. 5.15). This