冲泻区形态动力学耦合模型研究Ⅱ:模型建立与验证

Coupled swash zone hydrodynamics and beach morphodynamics modeling Ⅱ. Model establishment & validation

利用已建立的分段输沙率公式和实验数据,基于一维非线性浅水方程和床面变形方程,考虑两类共6种输沙率公式,增加床面剪切应力和渗流源项,建立适用于冲泻区水沙动力特性的岸滩形态动力学耦合模型。采用典型算例对模型可靠性进行了数值验证,结果表明,耦合模型中采用TVD-WAF格式和分段输沙率公式在计算形态变化时取得了较好的数值精度。进一步模拟了冲泻区内岸滩形态的变化特征,计算得到的水深、岸线轨迹和岸滩剖面变化结果与实验结果吻合较好,并讨论了不同摩阻系数和有无渗流对岸滩形态的影响规律,结果表明冲泻区形态动力学模型不能忽略床面摩阻和渗流的影响,本研究提出的分段输沙率公式适应于冲泻区的泥沙输运研究。

Based on the one-dimensional nonlinear shallow water equations and the bed deformation equation,this study considers two types(a total of six) of different sediment transport rate formulas,and implants the bed shear stress and seepage source terms to the equations,and finally a more complete model of swash zone hydrodynamics and beach morphodynamics is proposed,in which a coupled solution was realized. The model reliability is numerically verified based on the classical benchmark. The verification resultsshow that the TVD-WAF format and the segmental sand transport rate formula used in the proposed cou-pling model have achieved good solutions in numerical accuracy and morphological changes,which are bet-ter than previous research results. On this basis,this model is used to carry out numerical investigation ofsmash zone hydrodynamics and beach profile evolution. The results of depth,shoreline trajectory and shore-line profile are in good agreement with the experimental results,and then the study focused on the effectsof different friction coefficients and the presence of seepage on beach morphologies. The results indicatethat the segmental sediment transport rate formula proposed in this study is suitable for the study of sediment transport in the swash zone,and the effects of bed friction and seepage should not be ignored during established the beach morphodynamics model of swash zone.