Quantifying wake dynamics subjected to stream vegetation patch elongation: The influence of patch-edge vortices.

This article focuses on the influence of patch-edge Kelvin–Helmholtz (KH) vortices on wake flow structures generated by in-stream rectangular vegetation patches in aquatic environments. Through laboratory flume experiments varying patch density and aspect ratio, the study demonstrates that patch elongation not only adjusts bleed flow velocity deficit but also triggers KH vortices along patch lateral edges, which in turn accelerate steady wake velocity, shorten steady wake length, and dampen the energy of wake von Karman (VK) vortices. The initiation of patch-edge KH vortices is shown to be sensitive to the patch aspect ratio combined with velocity differences across the patch interface, and wake flow characteristics can be quantitatively predicted by a parameter integrating these effects. These findings enhance understanding of flow-vegetation interactions relevant to sediment transport, landscape evolution, and water quality management in vegetated aquatic systems.