Sensitivity of numerical parameters on DEM predictions of sediment transport

The current work presents a sensitivity study of selected numerical parameters on the large-eddy simulation-discrete element method predictions of sediment transport in a unidirectional open turbulent channel. The sensitivity of the particle friction factor, restitution coefficient, and spring stiffness used in the soft sphere collision model is tested in the three regimes of sediment transport comprising of essentially no motion, bed load, and suspended load flow regimes. The simulations are run for 10 s using base values of the parameters of interest (reference calculation), then one parameter is changed at a time and the corresponding change in quantitative result is observed for the following 15 s where averaged results in the last 10 s are compared to the reference calculation. The sensitivity analysis shows that the underpredicted sediment transport in the suspended load regime can be bridged by moderately decreasing the friction factor of the particles from 0.6 to 0.25. The impact of the same change in bed load regime is not as significant. Both the coefficient of restitution and the particle stiffness show less significant to negligible impact as compared to the friction factor.