MIXING IN SURF ZONE
MIXING IN SURF ZONE
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DOI：
10.1029/jc076i015p03493
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发表时间：
1971-01-01
影响因子：
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通讯作者：
NORDSTROM, CE
中科院分区：
文献类型：
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作者：
INMAN, DL;TAIT, RJ;NORDSTROM, CE
两个重要的混合机制在碎波带内起作用，每个机制都具有由波的强度和碎波带的尺寸确定的独特的长度和时间尺度。第一种是与破碎波及其孔相关，其在离岸方向上产生快速混合。这种混合，当在碎波带宽度Xb上进行归一化和平均时，给出了HbXb/T量级的涡流扩散系数，其中HbXb和T是碎波高度和波浪周期。第二个过程是平流，并与沿岸和离岸流系统在近岸环流圈。对于单元间的恒定沿岸排水量Qi，该过程给出了来自连续注入染料源的第n个单元下游的浓度Nn = N 0（Qi/Qm）n，其中N 0是离开注入单元的浓度，Qm是单元内的最大沿岸排水量。作为一种近似，浓度随着距离注入点y的增加而呈指数下降，当用y/Y代替时，其中Y是裂流之间的间距。这个关系式给出了一个数量级为Y的沿岸涡动混合系数，这里的Y是沿岸流速。沿着海洋海滩，HbXb/Tan和Y分别约为10 m2 sec-1和100 m2 sec-1。
Two important mixing mechanisms are operative within the surf zone, each having distinctive length and time scales determined by the intensity of the waves and the dimensions of the surf zone. The first is associated with the breaking wave and its bore, which produce rapid mixing in an on‐offshore direction. This mixing, when normalized and averaged over the surf zone widthXb, gives coefficients of eddy diffusivity of the order ofHbXb/TwhereHbandTare the breaker height and the period of the waves. The second process is advective and is associated with the longshore and rip current systems in the nearshore circulation cell. For constant longshore discharge of water between cellsQi, this process gives a concentrationNnin the nth cell down‐current from a continuously injected source of dye ofNn=N0(Qi/Qm)nwhereN0is the concentration leaving the injection cell, andQmis the maximum longshore discharge within a cell. As an approximation, the concentration decreases exponentially with distanceyfrom the injection point whennis replaced byy/Y, whereYis the spacing between rip currents. This relation gives an apparent longshore eddy mixing coefficient of the order ofY<υi> where <υi> is the longshore current velocity. Along ocean beachesHbXb/TandY<υi> are about 10 m2sec−1and 100 m2sec−1respectively.