Three–dimensional computation of turbulent flow in meandering channels and rivers

Abstract

In this paper, a three–dimensional (3D) numerical model for the computation of turbulent meandering flow is developed. A finite element calculation procedure combined with the two–equation k–ε and mixing length model are applied to the problem of simulating the 3D turbulent flow in closed and open curved channels. Near the wall a special approach is applied in order to overcome the weakness of the standard k–ε model in the viscous sub–layer. A special shape function is used in the near wall elements to accurately describe the strong variations of the mean flow variables in the viscosity–affected near wall region. At the free surface, a moving boundary condition combined with the surface tracking procedure is applied to determine the position of the free surface. Eventually, in order to solve a large nonlinear equation system, which is obtained from the discretization of the continuity and momentum equations, a segregated approach is applied. The segregated solver is guaranteed to have substantially reduced disk storage in comparison with a fully coupled solver.

Keywords:

• Meandering channels
• finite element method
• turbulent flow
• free surface tracking