A MIXING MECHANISM IN THE NEARSHORE REGION

[摘要] A dispersive mixing caused by the interaction of the longshore currents and the undertow is found to exist in the nearshore region. It is found to depend critically on the depth variation of both the cross-shore and the longshore currents. The effect is calculated for the simplest possible current profiles which yield a non-zero contribution. It is demonstrated that the dispersive mixing totally dominates the mixing in the nearshore region, exceeding the effect of turbulence by an order of magnitude even inside the surf-zone. In consequence, accounting for this interaction of the nearshore currents makes it possible to model longshore currents using realistic turbulent mixing levels. The vertical variation of those currents become part of the results provided. The predicted depth variation of the longshore currents is shown to be consistent with the only set of such measurements presently available.

[学科分类] 建筑学

[关键词] mixing mechanism;nearshore region