Numerical study of the effect of vegetation submerged ratio on turbulence characteristics in sediment-laden flow

Abstract

This study examines the flow and suspended sediment characteristics in sediment-laden flows under various vegetation submergence ratios (SRs), focusing on the evolution trends of turbulence characteristics with different SRs. The analysis of sediment-laden flow is performed by integrating the drift flux model with a vegetation source term, while the turbulence characteristics are simulated using the $k-\omega$ SST-IDDES turbulence model. The findings indicated that as the vegetation SR increases, the distributions of turbulent kinetic energy (TKE) and turbulent shear stress (TSS) in vertical and horizontal planes become more intense and intricate, exhibiting more pronounced peaks. Matrix cross-correlation analysis of the vertical TKE and TSS fields reveals a strong negative correlation in most of the same region, which ascends as the SR increases. The horizontal TKE and TSS distributions on both sides show a strong negative correlation. Statistical analysis revealed that higher SRs increase vertical TKE above the canopy but suppress vertical TKE within the canopy, while the transverse TKE intensity remains symmetric but non-uniform. The intensity of TSS also escalates as the SR increases. Vertical TSS distribution exhibits extreme values at the flume bottom and near the canopy top, with near-canopy extremes consistently positioned slightly above the canopy top.