Influence of Water Depth Ratio of Upstream and Downstream on the Evolution of Maximum Wave Heights For Dam-break flow
Understanding the maximum wave height of a dam-break flow and its attenuation process during dam failure in reservoirs is cru-cial for downstream flood risk management.In this study,we conducted experiments using a large-scale flume(length 32m,width 1m,height 1.2m)to measure wave height variations over time and space during dam-break flow evolution.We investigated the effects of different water depth ratio of upstream and downstream(α)and slopes(S)on the evolution pattern of maximum wave height,wave velocity,and at-tenuation rate.The study results demonstrate a high correlation between the evolution of dam-break flow and the water depth ratio of up-stream and downstream,α.This correlation is primarily manifested in two typical patterns:bore wave and undular wave.When α<0.4,the dam-break flow evolves in the form of a bore wave,rapidly ascending to the stable water level.During this phase,the wave amplitude re-mains small,and the water surface exhibits minimal fluctuations.When α≥0.4,the dam-break flow evolves in the form of an undular wave.During this phase,the wave rapidly ascends to its maximum value and subsequently decays.At this time,the amplitude of the dam-break flow is large,and the water surface exhibits regular fluctuations.The variations in slope(S)and the water depth ratio of upstream and down-stream(α)significantly impact wave speed and growth rate.In scenarios with the same water depth ratio of upstream and downstream(α),an increase in slope(S)leads to higher wave velocity and growth rate.Conversely,when considering the same(S),an increase in the water depth ratio of upstream and downstream(α)results in larger wave velocity but reduced growth rate.The Levenberg-Marquardt algorithm is employed to analyze the maximum wave height evolution curve for(α=0.4～0.8).Nonlinear regression analysis is conducted to derive the maximum wave height attenuation formula.This formula is subsequently validated through numerical simulations at(x=21 m),demonstrat-ing good agreement between the formula and the numerical results.When the upstream and downstream water depth ratio(α>0.4),the max-imum wave height attenuation rate of the dam-break flow exhibits an initial rapid attenuation for the first wave,followed by a gradual de-crease to 0.The research results contribute to a deeper understanding of the dam-break flow evolution process and establish a theoretical foundation for the field of dam-break flow catastrophic disaster science.
dam-break flowwater depth ratioslopehydrodynamic featureslaw of evolution
万方数据
维普
