Abstract
This paper presents numerical simulations of tracer particle transport both in the absence and presence of free bars. The transport and diffusion of tracer particles is affected by both the probabilistic motion of sediment particles and by the river bed geometry associated with free bars. We compare results of numerical models using an equilibrium (flux-based model) and a non-equilibrium (entrainment-based model) conservation formulation for river bed variation associated with bedload transport. The results show that 1) the entrainment-based morphodynamic model successfully reproduces free bar formation, 2) the flux-based morphodynamic model fails to simulate tracer diffusion in the absence of bars, and 3) free bar formation enhances streamwise tracer diffusion.
