Analysis of the correlation between vegetated flow and suspended sediment using the drift flux model

Abstract

We propose a model that integrates a drift flux model with a vegetation source term and the k−ω shear stress transport with improved delayed detached eddy simulation turbulence model to simulate sediment-laden vegetated flows. The numerical model was validated using experimental data from Lu [“Experimental study on suspended sediment distribution in flow with rigid vegetation,” Ph.D. thesis (Hohai University, Nanjing, Jiangsu, China, 2008)] and Wang and Qian [“Velocity profiles of sediment-laden flow,” Int. J. Sediment Res. 7, 27–58 (1992)]. We analyzed the vertical profile characteristics and spatial distribution features of sediment-laden vegetated flows at different vegetation densities. A detailed analysis was conducted on the correlations between variables that could affect the suspended sediment distribution, including vorticity, vertical velocity, Reynolds stress, and turbulent kinetic energy (TKE) fields. It was found that the vorticity field is primarily correlated with the suspended sediment concentration (SSC) field at the vegetation canopy, while the vertical velocity field above the canopy has a positive correlation with the SSC field. Both the Reynolds stress and TKE fields above the canopy exhibit positive correlations with the sediment concentration field. However, below the canopy, both fields show negative correlations with the sediment concentration. The TKE field is closely related to the suspended sediment distribution near the bottom, whereas the Reynolds stress field influences the suspended sediment distribution near the surface. The overall correlation between Reynolds stress and TKE with sediment concentration is negative, with their correlation significantly higher than that of vorticity and vertical velocity, indicating a closer connection with the movement of suspended sediments than the other variables.