Pulsation effects on pollutant and sediment transport in free-surface flow

International audienceA series of numerical simulations are performed to study the pollutant and sediment transport in free surface channel flow. The present paper examines the dispersion of passive contaminants injected from a time periodic source in a fully developed turbulent flow. More precisely, the pulsation effects on the distribution behaviors of dissolved and particulate pollutants are analyzed and discussed. Simulations are carried out using a commercial Computational Fluid Dynamic (CFD) code, Fluent 6.3, which is based on the finite volume approach. The standard k-epsilon turbulence closure model is selected to simulate the turbulence generation and the Volume of Fluid (VOF) method is used to accurately capture the time varying free surface. The Discrete Phase Model (DPM) is used for capturing the movement of particles. Numerical results show that increasing pulsation amplitude and decreasing frequency generates higher dispersive effects in the concentration profiles of a dissolved pollutant. It is also concluded that, unlike dissolved substances, the particle transportation can be enhanced only for certain combinations of the pulsation amplitude and frequency due to the synchronization of the particle's movement with the oscillating potential. Increasing pulsation amplitude and decreasing frequency generates higher dispersive effects. Particle transportation can be enhanced only for certain amplitude-frequency combinations. (C) 2016 Elsevier Ltd. All rights reserved