Time-Space Variations of Hydraulic Parameters and Mixing Processes at the Density interface of River Mouth Flows

在最后一年，也就是1990年3月，我进行了实际观察，分析了新数据，并结合过去的所有数据分析了结果。8月上旬，在特尾河的观测工作如期开始。但不幸的是，当时由于日本海的台风，天气恶化，北海道被低气压区擦过。由于大风大浪，我们无法观察到正常的两层流。因此，在理想的两层流中不可能得到雷诺应力的测量。由于今年的测量没有达到令人满意的程度，我们计划假定今年，并计划在1991年发表一份报告。然而，我们在宏观尺度问题的研究中获得了以下具有重要意义的结果。。控制相对于物理尺寸和时间的波动的两个参数K和F_d已经确定。其中K为河口平均深度与潮汐幅值的比较指数，F_d为密集流的弗劳德数。将过去和现在的观测资料绘制在K-F_d平面上，清楚地描述了河流流向和三种水流发生的条件，以及盐水入侵的极限。在这个项目的最后一年，我们使用非线性稳定性分析，澄清了界面波的增长，这是解释界面现象的线索，到弱非线性阶段。分析结果表明，界面的变化是由界面上方和下方流动的不稳定性引起的，这些不稳定性记录为界面波，并且由此产生的理论流线结构与观察到的流线结构几乎完全吻合。

In the last year, which ended March 1990, I performed the actual observations, analysis of the new data, and an analysis of the results combined with all data from the past. The observations began on schedule at the Teshio River in the first part of August. However, unfortunately, the weather deteriorated due to a typhoon in the Japan Sea at the time, and Hokkaido was grazed by a low pressure area. Because of the high winds and high waves, we were not able to observe normal two-layer flow. Accordingly, it was impossible to obtain measurements of Reynolds stress in ideal two-layer flow. As the measurements of this year were not performed to satisfaction, we plan to presume this year, and plan to publish a report in 1991. However,, we have obtained following results of major significance in our studies of macroscale problems.The two parameters K and F_d which control fluctuations with respect to physical dimensions and time have been definitively determined. Here K is a comparative index between the average depth at the river mouth and the amplitude of the tide while F_d is the Froude number of the dense flow. When data from observations both past and present is plotted on the K-F_d plane, the conditions governing direction of flow of the river and the occurrence of the three kinds of flow, and the limits of intrusion of salt water are clearly described.During the final year of this program using nonlinear stability analysis, we clarified the growth of interfacial waves, a clue to the explanation of interfacial phenomena, to the weakly nonlinear stage. Results of the analysis showed that transformations in the interface were brought about by instabilities in the flows immediately above and below the interface, that these register as interfacial waves, and that the resulting theoretical streamline structure matches nearly perfectly with the observed one.