Effect Of Roughness On Numerical Solution Of Saint-Venant Equations

In recent years, it's always seen the unusual phenomenon of flood's peak discharge increasing while routing at the Lower Yellow River. According to the current study, it may be related to the roughness'slight change due to the interaction between stream and sediments. It will not only help to explain the phenomenon through the analysis of the impact of roughness's slight change on the numerical solution of Saint-Venant equations, but also has theoretical value.The thesis focuses on the following aspects,(1) 1D and 2D Saint-Venant equations of unsteady open channel flow are given.(2) The Finite Volume method and orthogonal staggered grid are used to divide the solution domain.(3) With sub-relaxation technique and TDMA algorithm, the coupled field of the water depth and velocity are iteratively solved by SIMPLE algorithm.(4) Under the condition of clear water and after initial and boundary conditions introduced, the flood routing is simulated as to different roughness values.(5) The numerical simulation results are summarized and analyzed to discuss the unusual phenomenon due to slight change of roughness or discharge integration.