TY - JOUR
T1 - Modelling Turbulent Coherent Structures in Lateral River Cavities using Large-Eddy Simulation and a High-Order 2D Shallow Water Model
AU - Ouro, Pablo
AU - Navas-Montilla, Adrian
AU - Franca, Mario J.
AU - Juez, Carmelo
N1 - Publisher Copyright:
© 2022 IAHR.
PY - 2022
Y1 - 2022
N2 - The hydrodynamic processes developed at the interference of rectangular lateral cavities and the main channel in rivers or canals drive the mass and momentum exchange, which are responsible for sediment deposition or nutrient transport. The geometric characteristics of the cavities, namely their relative longitudinal and transverse extensions to the river width, determine how the mixing between lateral cavities and main channel occurs since these condition the flow phenomena developed at the shear layers. In square-shaped cavities, a single large-scale recirculating eddy develops within the cavities with Kelvin-Helmholtz vortices formed over the mouth of the cavity. We investigate the performance of two state-of-the-art numerical approaches, namely large-eddy simulations (LES) and a two-dimensional depth-averaged shallow water model based on a high-order WENO scheme, to predict the unsteady hydrodynamics and governing turbulent structures developed within lateral river cavities for a square-like configuration with 0.8 aspect ratio. Despite the relatively shallow conditions, the developed flow is highly three-dimensional, thus we quantified the ability of the LES and high-order WENO models to represent the governing flow mechanisms over the main channel, in-cavity flow and at the transition between them. We compare the characteristics of the shear layers captured by the different models, e.g. frequency of Kelvin-Helmholtz vortices or transverse velocity oscillations. Our results provide a better understanding of how the complex fluid mechanics in lateral cavities built in river banks can be captured with models of increasing complexity and accuracy.
AB - The hydrodynamic processes developed at the interference of rectangular lateral cavities and the main channel in rivers or canals drive the mass and momentum exchange, which are responsible for sediment deposition or nutrient transport. The geometric characteristics of the cavities, namely their relative longitudinal and transverse extensions to the river width, determine how the mixing between lateral cavities and main channel occurs since these condition the flow phenomena developed at the shear layers. In square-shaped cavities, a single large-scale recirculating eddy develops within the cavities with Kelvin-Helmholtz vortices formed over the mouth of the cavity. We investigate the performance of two state-of-the-art numerical approaches, namely large-eddy simulations (LES) and a two-dimensional depth-averaged shallow water model based on a high-order WENO scheme, to predict the unsteady hydrodynamics and governing turbulent structures developed within lateral river cavities for a square-like configuration with 0.8 aspect ratio. Despite the relatively shallow conditions, the developed flow is highly three-dimensional, thus we quantified the ability of the LES and high-order WENO models to represent the governing flow mechanisms over the main channel, in-cavity flow and at the transition between them. We compare the characteristics of the shear layers captured by the different models, e.g. frequency of Kelvin-Helmholtz vortices or transverse velocity oscillations. Our results provide a better understanding of how the complex fluid mechanics in lateral cavities built in river banks can be captured with models of increasing complexity and accuracy.
KW - Cavities
KW - Free-surface
KW - Large-eddy simulation
KW - Shallow-water model
KW - Turbulence
UR - http://www.scopus.com/inward/record.url?scp=85177228545&partnerID=8YFLogxK
U2 - 10.3850/IAHR-39WC2521716X2022195
DO - 10.3850/IAHR-39WC2521716X2022195
M3 - Conference article
AN - SCOPUS:85177228545
SN - 2521-7119
SP - 3647
EP - 3653
JO - Proceedings of the IAHR World Congress
JF - Proceedings of the IAHR World Congress
T2 - 39th IAHR World Congress, 2022
Y2 - 19 June 2022 through 24 June 2022
ER -