常曲率窄深型弯曲河流水流动力稳定特征理论研究
摘要
The meander river is the one of the most common type in natural river morphology. Its flow pattern influences transformation and development of river morphology. A preliminary theory of the transition from laminar to turbulent flow in a narrow and deep meander channel with constant curvature is investigated in this paper. A new velocity distribution formula of laminar flow and a formula of critical Reynolds number against bend curvature were found. These formulas will be valuable to bend channel design. The analyses on relevant parameters reveal that the curvature can play an important part in flow stability. The neutral curve will move rightward and the critical Reynolds number increase with bank curvature increasing. The flow is unstable in response to a narrower range of disturbance wave number; therefore, the flow can maintain stability as laminar flow. These results establish the fundamental theory to further study ‘point bar’ and ‘free bar’ in meandering rivers.