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Modelling transverse solute mixing across a vegetation generated shear layer

Author(s): Patrick O. West; Virginia R. Stovin; James R. Hart; Ian Guymer; Frederick C. Sonnenwald; Stephen G. Wallis

Linked Author(s): Stephen Wallis, Ian Guymer, Fred Sonnenwald

Keywords: Dispersion; Finite difference model; Mixing; Shear effects; Vegetation

Abstract: Transverse solute mixing across a vegetation generated horizontal shear layer was quantified using laser induced fluorometry techniques for artificial and real vegetation. A two-dimensional finite difference model (FDM) was developed to describe transverse concentration profiles for flows containing transverse variations in velocity and transverse dispersion, from a steady solute input. The FDM was employed inversely, to optimize the parameters describing the transverse distribution of the transverse dispersion coefficient for vegetation generated shear layers. When laboratory data are available, continuous function descriptions produce slightly improved FDM modelled solute concentration profiles compared with simplified step discontinuity velocity and dispersion inputs. When laboratory data are not available, estimates of step or continuous transverse distributions from other work enable concentration profiles to be predicted with a similar goodness of fit. This paper presents a validated, simple, robust finite difference model to describe the mixing of solutes in a channel containing marginal vegetation.


Year: 2021

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