3-D Flood Flow Structures in a Doubly Meandering Compound Channel under Dominant Relative Depth
| Autor: | Yoshihisa Kawahara, Nobuyuki Tamai, G. M. Tarekul Islam |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Journal of applied mechanics. 11:735-743 |
| ISSN: | 1884-832X 1345-9139 |
| Popis: | A doubly meandering compound channel is one in which both lower and upper channel meander. This paper examines the 3-D flood flow structures in terms of primary velocity distribution, stream-wise velocity distribution and secondary currents in a doubly meandering compound channel under dominant relative depth. The relative depth is the ratio of the depth of water over the floodplain to the total depth of water while the dominant relative depth is the relative depth at which the difference in discharge between the rising and falling stages takes the maximum value. The dominant relative depth of a doubly meandering compound channel is found to be 0.17. The primary velocity distribution under the dominant relative depth appears to be essentially the same for both rising and falling stages. The exchange of flow between main channel and floodplain results in the retardation and deviation of flow fields. The extent of retardation and the angle of deviation of the stream-wise velocity vary in the rising and falling stages. The maximum retardation occurs in the cross-over section at the floodplain level for both rising and falling stages. The maximum deviation occurs at the bend apex section for both rising and falling stages. The magnitude of the secondary current under dominant relative depth can be as high as 30% of the bulk velocity. The evolution and decay processes of secondary currents during rising and falling stages are essentially the same but only differ in strength. |
| Databáze: | OpenAIRE |
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