A REASSESSMENT OF THE ROLE OF TIDAL DISPERSION IN ESTUARIES AND BAYS
A REASSESSMENT OF THE ROLE OF TIDAL DISPERSION IN ESTUARIES AND BAYS
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DOI：
10.2307/1352684
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发表时间：
1992-06-01
期刊：
影响因子：
--
通讯作者：
SIGNELL, RP
中科院分区：
文献类型：
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作者：
GEYER, WR;SIGNELL, RP
潮汐分散的作用进行了重新评估，考虑相关的物理机制，特别是那些阐明了潮汐引起的分散的数值模拟的基础上。看来潮流对分散的主要影响发生在潮汐漂移的长度尺度或更小的尺度上;因此，潮汐分散的有效性取决于潮汐漂移与主要水深和海岸线特征之间的间距的相对尺度。在河口的地形特征的典型间距小于潮汐漂移，潮汐分散可能会显着地促进整体冲洗。在河口和海湾中，主要特征之间的典型间距大于潮汐漂移，潮汐分散的影响将是局部的，它不会显着地有助于整体冲洗。潮汐分散在地形突变的地区最为明显，如岬和入口，在那里会发生水流分离。在流动分离区域的强应变率倾向于将流体的斑块拉伸成长的细丝，这些细丝随后被瞬态涡流场卷起和扭曲。由潮汐完成的分散过程作为位置和潮汐相位的函数变化很大，因此不适合用涡流扩散系数进行参数化。
The role of tidal dispersion is reassessed, based on a consideration of the relevant physical mechanisms, particularly those elucidated by numerical simulations of tide-induced dispersion. It appears that the principal influence of tidal currents on dispersion occurs at length scales of the tidal excursion and smaller; thus the effectiveness of tidal dispersion depends on the relative scale of the tidal excursion to the spacing between major bathymetric and shoreline features. In estuaries where the typical spacing of topographic features is less than the tidal excursion, tidal dispersion may contribute significantly to the overall flushing. In estuaries and embayments in which the typical spacing between major features is larger than the tidal excursion, the influence of tidal dispersion will be localized, and it will not markedly contribute to overall flushing. Tidal dispersion is most pronounced in regions of abrupt topographic changes such as headlands and inlets, where flow separation occurs. The strong strain rate in the region of flow separation tends to stretch patches of fluid into long filaments, which are subsequently rolled up and distorted by the transient eddy field. The dispersion process accomplished by the tides varies strongly as a function of position and tidal phase and thus does not lend itself to parameterization by an eddy diffusion coefficient.