Xiaowan Reservoir was created by the construction of Xiaowan Dam on Mekong River. This dam is the second highest arch dam in the world with 292 m tall and 902 m long. The reservoir is about 178km from upstream to the dam, and the surface area is around 189 km~2. The water depth near the dam is very deep, which normally varies from 200 to 270m seasonally. For such a deep reservoir, the vertical temperature distribution show a significant stratified structure. In this study, a three dimensional numerical model was developed for simulating the flow fields and temperature distribution in Xiaowan reservoir near the dam. The effects of buoyancy on the momentum equations and turbulence transport equations was considered. For turbulence closure, the buoyancy-extended version of k-e model was used. The model was first validated using a laboratory case of turbulent buoyant flow in a curved open channel, and then it was applied to simulate the flow and temperature in Xiaowan Reservoir. The numerical results were compared with field measurements, and the physical characteristics of flow pattern and temperature distribution in the reservoir were discussed.
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