Hydraulic characteristic on flow field and sediment movement inside and outside seagrass fields

为了获得重现海区消失海草场的一些信息，进行了室内实验和野外观测。利用图像技术测量了模型海草间悬浮泥沙浓度。悬浮物的分布和粒径可以同时测定。结果表明，颗粒粒径在运动初期大于中等粒径，中心粒径的颗粒随着时间的增加而运动。为了在数值模拟中考虑运动目标的影响，采用了包裹判断法。提出了一种测量硅球多孔介质内部及其附近流体运动的方法。采用碘化钠溶液作为折射率匹配液。为了捕获图像，提出了一种分辨率PIV方法，并给出了速度场和湍流运动学能量的实验结果。讨论了多孔介质内部及附近流场的结构。并对湍流的产生和消散机理进行了探讨。对赤石市英岛海滩形成的海草场进行了实地观测。由于生长茂盛的时期过去了，海草枯死了很多。PH值与溶解氧之间存在明显的相关性，认为这是受白天光合作用的影响。此外，受附近海底森林的影响，水流速度下降

To obtain some information to reproduce the disappearing seagrass field in the sea area, the laboratory experiment and the field observation have been conducted. The suspended sediment concentration among model seagrasses has been measured by using image technique. The distribution of suspended sediment and the grain size could be measured simultaneously. It turned out that the particle size was bigger than medium grain size at the beginning of its movement, the particle of a central particle size moved with the increasing of time. To consider the effect of the movement object into the numerical simulation, the wrapping judgment method was used. A measuring method of fluid motion inside and in the vicinity of porous media of silicon spheres is presented. Sodium iodide solution is used as the refraction index matching fluid. In order to capture pictures, a resolution PIV method Some experimental results on the velocity field and turbulence kinemaatic energy are presented. Structure of the flow field inside and in the vicinity of the porous media is discussed. Moreover generation and dissipation mechanism of the turbulence was discussed.A field observation has been executed over the seagrass field formed at Eigashima beach in Akeshi City. There were a lot of died seagrass because the growing thickly period had been passed at time. There are clear correlations in PH and DO, and it is thought the influence of the photosynthesis in daytime. Moreover, the decrease at flow velocity was observed by the influence of the marine forest in the bottom of the sea neighborhood