New Near-Wall Treatment for Suspended Sediment Transport Simulations with High Reynolds Number Turbulence Models

A new approach is proposed to treat the bottom boundary conditions for suspended sediment transport modeling, which works with turbulence models using wall functions. New boundary conditions for suspended sediment are specified directly at the sediment bed, not at some reference height. It is numerically equivalent to the traditional approach of specifying boundary condition at a reference height. The new approach eliminates the need of any special treatment for the gap between the bed and the reference height. It also reduces the loss of accuracy due to the interpolation of solution variables between the meshes for fluid and suspended sediment. The associated near-bottom grid resolution requirement is discussed and a general guideline is proposed. The application of the new near-wall treatment is demonstrated.