A13. Waves in a slanting current field
A stationary, 1-d, deep water case is considered, where the current velocity
in y-direction varies with x.
At the W boundary the current velocity is 0, the regular incoming waves
have a period of 6.35 s and an angle of 60°.
In the domain the Uy varies linearly with x; the coefficient
of proportionality is 0.01 (m/s/m).
The theory shows that a caustic will develop on a line x=79.3 m.
4 cases are considered:
The graph also indicates the line along which the caustic is expected to be present. The theory supposes a regular wave field, so a very narrow spectrum is used.
Due to the fInite width of this spectrum the behaviour near the caustic is smooth where the theory forecasts a discontinuous behaviour. The three graphs of analytic solutions (incident directions 55, 60 and 65 degrees) show that the position of the caustic is very sensitive to the incident wave direction.
No explanation has been found for the fact that the computed wave heights for low values of x are above 1.
The second and third panel show the computed and analytic wave directions:
panel 2: average wave directions (crest normal directions),
panel 3: energy transport directions (i.e. directions of the
energy transport vector).