2013 栃木県黒川における氾濫要因の数値解析(G05-6 流体工学(6)数値流体解析,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

概要

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Heavy rain has concentrated in Nasu area in Tochigi prefecture on August 26^<th>, 1998. The maximum precipitation of 607 nun in a day has been recorded at Nasu weather observatory on August 27^<th>. This heavy rain had Kurokawa and Yosasa rivers flood and a great number of houses have been suffered from flooding. In order to prevent threat of natural disaster, it is important to deepen the knowledge of flooding mechanism. From this point of view, numerical analysis has been performed for selected flow region of Kurokawa river in compound meandering open-channel flow by using algebraic Reynolds stress model. The turbulent flow in actual flooding river is one of the complicated turbulent flows, because the flow behavior is influenced upon many kinds of forces. Calculated results suggest that flooding is caused by accelerated flow near the free surface which appears at upstream of sharp-turn open channel. This accelerated flow is generated by the reduction of cross sectional area which is induced by the separated flow near the river bed.
2008-08-02