Author(s): Jingfang Qu; Jie Yu

Linked Author(s):

Keywords: Bulk vegetation resistance; Kelvin–Helmholtz instability; Patch-scale von Kármán vortices; Vegetated open channel; Wake and bleed flows

Abstract: Simulations of shallow-water flows in an open channel with vegetation are considered. The simple formulation of bulk resistance makes numerical realization of vegetation straightforward. Stem-scale eddies due to individual plants are not modelled. While the vegetation resistance parameterization has been frequently used, few studies exist that comprehensively evaluate the modelling skills of such a highly simplified approach in capturing the large-scale dynamics which are often of practical interest. This study provides such an assessment by conducting a range of comparisons between the simulations and data. While the simple model is remarkably effective, capturing the large-scale features that are comparable with the data (e.g. the two-layer structure of the shear layer resulting from the Kelvin–Helmholtz instability at the canopy–water interface, the steady wake behind a vegetation patch and formation of patch-scale von Karman vortices), we emphasize the discrepancies in some aspects. These findings inform large-scale modelling and the needs for improvement.

DOI: https://doi.org/10.1080/00221686.2020.1770877

Year: 2021