TY - GEN
T1 - Large Eddy simulation (LES) of flow and bedload transport at an idealized 90-degree diversion
T2 - International Conference on Fluvial Hydraulics, RIVER FLOW 2016
AU - Dutta, Som
AU - Fischer, Paul
AU - Garcia, Marcelo H.
N1 - Funding Information:
The authors would like to thank the Ravi K. Kinra and Kavita Kinra Fellowship conferred by the Dept. of Civil and Environmental Engineering to the junior author, the fellowship allowed him to work on the current study. The authors would also like to thank Blue Waters, NCSA, University of Illinois at Urbana-Champaign for the time allocation on the Petascale supercomputer, without which it would have been impossible to complete the computationally intensive calculations in a reasonable time.
Publisher Copyright:
© 2016 Taylor & Francis Group, London.
PY - 2016
Y1 - 2016
N2 - Bifurcations are an integral part of river systems, thus better understanding of the dynamics flow and sediment transport is important for accurate prediction of the long-term geomorphological evolution of these systems. A class of bifurcations in which one of the bifurcating channels continues along the direction of the main channel, and the other comes out laterally, is also referred to as diversion. In 1926, Bulle conducted the first study that quantified the hydrodynamics and bedload transport at a diversion, and to this day his study remains one of the most extensive studies on the topic. Bulle put forth the phenomena of preferential movement of near-bed sediment at a diversion towards the lateral channel, thus this phenomenon is often referred to as the Bulle-Effect. In the current study, the governing mechanism of Bulle-Effect has been explored by conducting LES of the flow and bedload transport at an idealized 90-degree diversion. The scale of the simulated diversion and the bulk Reynolds number are similar to the experiments conducted by Bulle. The simulation was conducted using the open-source spectral element based Navier-Stokes solver Nek5000. Bed load transport was modeled using the Lagrangian particle tracking method. The simulation results clearly portray the tendency of the near bed currents at the bifurcation to move into the side-channel, consequently taking most of the near-bed sediment along with it. The results also affirm the presence of vortices in the both the channels after the diversion. The Dynamics of bedload transport at the bifurcation was captured successfully, with the percentage of total sediment entering the side-channel matching Bulle’s experimental observation. Apart from taking a detailed look at the mechanism behind Bulle-Effect, the current study is also one of the first to use highresolution LES and Lagrangian particle dynamics to study the hydrodynamics and bed-load transport dynamics at an experimental scale bifurcation.
AB - Bifurcations are an integral part of river systems, thus better understanding of the dynamics flow and sediment transport is important for accurate prediction of the long-term geomorphological evolution of these systems. A class of bifurcations in which one of the bifurcating channels continues along the direction of the main channel, and the other comes out laterally, is also referred to as diversion. In 1926, Bulle conducted the first study that quantified the hydrodynamics and bedload transport at a diversion, and to this day his study remains one of the most extensive studies on the topic. Bulle put forth the phenomena of preferential movement of near-bed sediment at a diversion towards the lateral channel, thus this phenomenon is often referred to as the Bulle-Effect. In the current study, the governing mechanism of Bulle-Effect has been explored by conducting LES of the flow and bedload transport at an idealized 90-degree diversion. The scale of the simulated diversion and the bulk Reynolds number are similar to the experiments conducted by Bulle. The simulation was conducted using the open-source spectral element based Navier-Stokes solver Nek5000. Bed load transport was modeled using the Lagrangian particle tracking method. The simulation results clearly portray the tendency of the near bed currents at the bifurcation to move into the side-channel, consequently taking most of the near-bed sediment along with it. The results also affirm the presence of vortices in the both the channels after the diversion. The Dynamics of bedload transport at the bifurcation was captured successfully, with the percentage of total sediment entering the side-channel matching Bulle’s experimental observation. Apart from taking a detailed look at the mechanism behind Bulle-Effect, the current study is also one of the first to use highresolution LES and Lagrangian particle dynamics to study the hydrodynamics and bed-load transport dynamics at an experimental scale bifurcation.
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U2 - 10.1201/9781315644479-20
DO - 10.1201/9781315644479-20
M3 - Conference contribution
AN - SCOPUS:85015265524
SN - 9781138029132
T3 - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
SP - 101
EP - 109
BT - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
A2 - Constantinescu, George
A2 - Garcia, Marcelo
A2 - Hanes, Dan
PB - CRC Press/Balkema
Y2 - 11 July 2016 through 14 July 2016
ER -