Case VII: 90° Change in Wind Direction

Abstract

A uniform wind blows to the north at 20 m/s over an infinite ocean until the sea is fully developed (f _P = f _PM, Case VIIa) or half-developed (f _P = 2 f _PM, Case VIIb). At this time (t = 0) the wind is instantly turned 90°, from north to west, at the same wind speed, 20 m/s. As the wind and wave fields are homogeneous in space, the wave models can be run, without the advection terms, at a single “grid point” as a function of time only. (Where this could not be readily implemented, the asymptotically homogeneous downwind limit of a space—time-dependent solution was taken, in analogy to the duration-limited results of Case II.)