不规则波情况下破波带内污染物水平二维输移扩散实验研究

An experimental study on horizontal two-dimensional transport and diffusivity of dye under irregular waves in surf zone

研究破波带内污染物输移扩散特性可为近岸水环境保护和污染物的排放设计提供依据。由于实际情况中海岸入射波都是不规则波,因此本文基于物理模型实验、图像处理和形心点追踪等方法对5组不规则入射波况下的污染物水平二维输移扩散特性进行了研究,着重对不同波况下污染物垂直岸线方向与沿岸方向的输移速度及垂直岸线方向的扩散系数进行了计算分析。结果表明,不规则入射波情况下污染物垂直岸线方向的输移速度Vx约为沿岸方向输移速度Vy的4.4%~64.7%;沿岸方向的污染物输移速度约为时均沿岸流速最大值的35%;在不规则波入射情况下,垂直岸线方向的扩散系数为2.3×10^(−4)~2.2×10^(−3)m^(2)/s,并且扩散系数随不规则入射波周期的增大而减小,而入射波波高对其影响并不显著。

The experimental study on transport and diffusivity of pollutant in the surf zone can provide a basis for the design of nearshore water environmental protection and pollutant discharge.In the actual situation,the coastal incident waves are irregular waves,this paper studies the horizontal two-dimensional transport and diffusivity of dye under five irregular incident waves based on physical model experiments,image processing and centroid tracking,focuses on the calculation and analysis of the transport velocity in the alongshore and the transport velocity and diffusion coefficient in the cross-shore direction of the dye patch under different wave conditions.The results show that the cross-shore dye transport velocity Vx is about 4.4%~64.7%of the alongshore direction Vy in the case of irregular incident waves;the alongshore dye transport velocity is about 35% of the mean longshore current maximum;the diffusion coefficient in the cross-shore direction is within the range of 2.3×10^(−4)~2.2×10^(−3)m^(2)/s under irregular waves,which is decreases as the increase of irregular incident wave period,and the incident wave height has no significant effect on it.