Flow Adjustment Through a Finite Patch of Submerged Flexible Vegetation by Flume Experiments

Aquatic vegetation, acting as a primary producer, plays a crucial role in the exchange of mass and energy in vegetated flow. However, considering the strong three-dimensional nature of the submerged flexible vegetation, there is a gap of the study on the flow adjustment induced by submerged flexible vegetation. Herein, vegetation is modified in form of pellet strings mimicking the nature species Cabomba caroliniana, the adjustment of flow field under different submergence depths and flow discharges were explored through flume experiments with a finite patch of submerged flexible vegetation. Statistics of instantaneous velocity were recorded by Acoustic Doppler Velocimeter (ADV), and turbulence parameters including turbulent kinetic energy (k), Reynold stress (− \(\overline{{{\mathbf{uw}}}}\) ) were calculated. The results show evolvements of mean velocity profile from a typical logarithmic boundary layer to the hyperbolic tangent mixing layer, and that the relative submergence does not affect the shear layer’s thickness and shape, only causing a horizontal shift of the profile along the axis. The horizonal turbulent velocities within the canopy display an isotropy, other turbulent characteristics show a local concentration around the top of the canopy. The findings provide an insight into the mechanism of responses between the flow and flexible vegetation and a reference for further study applying this form of plant model.