Vertical Profile Of Suspended Fine Sediment Concentration Under Breaking Waves

As wave breaking plays a significant role in suspending sediment, it should be taken into great consideration when the distribution of suspended sediment concentration is studied. Through experiments, a better understanding is gotten and some preliminary assumptions are supposed about the law of the distribution of suspended sediments, as shown in the framework of the dissertation below.Firstly, the vertical distribution of the suspended sediment concentration and time serial velocities of different depth measured by ADV are gotten in different section along the flume under the breaking waves in the experiment of the Huanghua Harbor's fine sediment and Lvju River's fine sediment; some phenomena and results of the experiment are gotten as follows: (1) Near wave breaking point, suspended concentration is approximately equal; the concentration near bottom just before wave breaking is higher than the concentration after wave breaking, then the average concentration of the section is higher, so it is very important to take the suspended concentration into consideration just before wave breaking; (2) Under plunging waves, the distance is very important relative to the distance under spilling waves, suspended concentration is larger when the distance is shorter, suspended concentration is smaller when the distance is longer; (3) In the inner region of the surf zone, the vertical distribution of suspended sediment concentration is approximately equal to one line with steep slope; (4) A high concentration layer near bottom before wave breaking is found, but this layer is disappeared after wave breaking; (5) The sediment medium diameters of one section is approximately equal under breaking waves; and under non-breaking waves the sediment medium diameter of one section near bottom is larger, and the sediment medium diameter becomes smaller when the distance to the bottom is farther.Secondly, turbulence dissipation rates and turbulence intensity are obtained by analyzing the time serial velocities measured by ADV using the inertial dissipation method of George. The results that the turbulence intensity is largest near the breaking point, the turbulence intensity becomes larger before wave breaking and becomes smaller after wave breaking along the flume are gotten by analyzing the distribution of turbulence intensity.Thirdly, the 1-D sediment diffusion equation is erected through simplifying the...