Multilayer Numerical Modeling of Flows through Vegetation Using a Mixing-Length Turbulence Model

Abstract

This work focuses on the effects of vegetation on a fluid flow pattern. In this numerical research, we verify the applicability of a simpler turbulence model than the commonly used k-ε model to predict the mean flow through vegetation. The novel characteristic of this turbulence model is that the horizontal mixing-length is explicitly calculated and coupled with a multi-layer approach for the vertical mixing-length, within a general three-dimensional eddy-viscosity formulation. This mixing-length turbulence model has been validated in previous works for different kinds of non-vegetated flows. The hydrodynamic numerical model used for simulations is based on the Reynolds-averaged Navier-Stokes equations for shallow water flows, where a vegetation shear stress term is considered to reproduce the effects of drag forces on flow. A second-order approximation is used for spatial discretization and a semi-implicit Lagrangian-Eulerian scheme is used for time discretization. In order to validate the numerical results, we compare them against experimental data reported in the literature. The comparisons are carried out for two cases of study: submerged vegetation and submerged and emergent vegetation, both within an open channel flow.

To Investigate the Flow Structure of Discontinuous Vegetation Patches of Two Vertically Different Layers in an Open Channel

“…It is visible that the velocity has maximum value above the vegetation zone. Hector Barrios-Pina et al [29], in their numerical investigation through double-layered vegetation, also found that the flow velocity rises above the vegetated region.…”

Hydrodynamic-Based Numerical Assessment of Flood Risk of Tamuín City, Mexico, by Tampaón River: A Forecast Considering Climate Change

“…where Cz is the Chezy coefficient. This hydrodynamic model has been calibrated according to Casulli and Cheng [92], and has been tested in [67,68,70,93].…”

“…In this work, we performed an assessment of the flooding risk of Tamuín city, through a parallel self-made hydrodynamic model previously validated in diverse studies [66][67][68][69][70] and carefully calibrated with field measurements, with the idea of having full control of processes, methods and precision provided by owning the code. Streamflow of Tampaón River in wet and dry seasons was simulated according to historical records.…”

Modelling Shallow Water Wakes Using a Hybrid Turbulence Model

“…Barrios-Pina et al [23] verified the applicability of a simpler turbulence model than the commonly usedmodel to predict the mean flow through vegetation in shallow waters. However, despite the great number of versions of turbulence models based mainly on mixing length, -, and algebraic, none can be used universally for all kinds of problems, as the scale of the study domain and the computer equipment available must be considered.…”