光滑壁面明渠水流的三维格子玻耳兹曼模拟

Simulation of Smooth Open Channel Flow by 3D Lattice Boltzmann Method

明渠水流与泥沙运动、河床演变等问题密切相关,明渠水流特征的研究对于揭示明渠水流作用下的泥沙运动机理具有十分重要的意义.为此,应用新型数值模拟方法三维格子玻耳兹曼方法对明渠均匀流进行了研究.首先介绍了格子玻耳兹曼方法的理论基础、边界条件处理以及流动的驱动方式,接着分别模拟了明渠层流和光滑壁面紊流的近底水流运动.结果表明,得到的明渠层流流速和切应力分布与解析解吻合较好,同时较好地反映了光滑壁面明渠紊流的流速分区结构、紊动特性和阻力规律,从而说明格子玻耳兹曼方法在明渠水流模拟中具有较好的适用性,为进一步采用该方法研究明渠流近底泥沙颗粒运动机理奠定了基础.

Abstract： Open channel flow has a close relationship with sediment transport and fluvial process, The study of the characteristics of open channel flow plays an important role in revealing the mechanism of sediment transport. A new promising numerical method, 3D lattice Boltzmann method, was applied to the research on uniform open channel flow. The theory of the lattice Boltzmann method, boundary treatment and flow generation were first introduced. Laminar open channel flow and the near-bottom hydrodynamics of smooth turbulent open channel flow were then simulated. Results indicated that the computed velocity and shear stress distribution agreed well with the analytical solution in laminar open channel flow simulation. They also well showed the velocity distribution, turbulence charac- teristics and friction law of smooth turbulent open channel flow. The lattice Boltzmann method was therefore proved feasible to the open channel flow simulation and provided the basis for the further research of sediment transport mechanism.