Velocity distribution characteristics for rigid vegetation model with spherical canopy: An analytical study adopting multiple mathematical methods

Abstract

Vegetation exists widely in natural rivers, resulting in unique characteristics of flow movement, affecting river flood processes and water quality. The flow movement of vegetated channels is defined as vegetated flow, and is currently receiving close attention. Influenced by vegetation, the classical logarithmic velocity profile turn into a more complex function according to the vegetation morphology and flow pattern. Several research teams have studied analytical models for simple cylinder-type vegetation; however, few studies have been conducted on analytical velocity models for vegetation with spherical canopy, and previous models cannot make accurate prediction of velocity profile in this case. To address this issue, new analytical models are proposed adopting the power series, exponential and trigonometric models. A comparison between the measured velocity profile and the analytical solution confirms that the newly proposed models are suitable for vegetation with spherical canopy. This analytical model can capture the vertical non-monotonic characteristics of velocity profile, which is what the previous models lack. Moreover, in contrast to numerical models, which require a lot of computational cost, this analytical model allows a quick and intuitive description of the flow profile, which provides hydrodynamic support for the restoration of vegetated channels.