基于欧拉-拉格朗日方法的明渠中悬移质淤积数值模拟

为了研究水利工程中悬移质泥沙淤积时的运动轨迹,基于欧拉-拉格朗日方法建立了三维悬移质泥沙输移数学模型,模型中采用标准k-ε湍流模型计算水流紊动流场,在拉格朗日坐标下计算泥沙颗粒轨迹,颗粒受力考虑了有效重力、阻力、虚拟质量力和Saffman升力。与传统的扩散模型和双流体模型相比,该模型摆脱了依赖泥沙浓度分布资料给定泥沙进口边界条件的局限性。使用该数学模型对经典的悬移质泥沙净淤积水槽实验进行了模拟,通过对计算的泥沙浓度垂向分布沿程变化与实验结果的对比,验证了数学模型的可靠性。模型还较好地模拟得到了实验中泥沙浓度在垂向上呈现的非单调变化。

Eulerian-Lagrangian simulations of suspended sediment deposition in open channels

A mathematical model for suspended sediment deposition has been developed based on an Eulerian-Lagrangian approach to explore the trajectories of suspended sediment particles in open channels. This model adopts a standard k-ε turbulence model for calculation of the turbulent flows and it calculates sediment particle tracks using a Lagrangian method and considering various forces on the particles, including: the effective gravitational force, drag force, virtual mass force and Saffman lift force. Compared with the traditional diffusion model and two-fluid model, the new model avoids the limitation on inflow sediment conditions that must be specified by measured sediment concentration distributions. Its prediction accuracy and reliability have been verified using a classical experiment of suspended load transport with net deposition, including a comparison between the predicted longitudinal variations of sediment concentration and measured ones. A non-monotonic vertical profile of sediment concentration that observed from the experiment has been also predicted with a good accuracy.