TY - JOUR
T1 - A detached eddy simulation model for the study of lateral separation zones along a large canyon-bound river
AU - Alvarez, Laura V.
AU - Schmeeckle, Mark
AU - Grams, Paul E.
N1 - Funding Information:
This research was supported by the U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and Research Center (GCMRC). Laura V. Alvarez was funded by Arizona State University's Graduate College Dissertation Fellowship and the School of Geographical Sciences and Urban Planning at Arizona State University. We are grateful to the editor Giovanni Coco (Editor), Bruce MacVicar (Associate Editor), and two anonymous reviewers. Their reviews and suggestions substantially improved the content and organization of this article. Scott Wright from U.S. Geological Survey and Matt Kaplinski from the School of Earth Science and Environmental Sustainability at Northern Arizona University are acknowledged for providing field survey data. The data were provided by the GCMRC upon personal request (website: www.gcmrc.gov). All the simulations were performed at the Arizona State University Advanced Computing Center (A2C2).
Publisher Copyright:
©2016. American Geophysical Union. All Rights Reserved.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Lateral flow separation occurs in rivers where banks exhibit strong curvature. In canyon-bound rivers, lateral recirculation zones are the principal storage of fine-sediment deposits. A parallelized, three-dimensional, turbulence-resolving model was developed to study the flow structures along lateral separation zones located in two pools along the Colorado River in Marble Canyon. The model employs the detached eddy simulation (DES) technique, which resolves turbulence structures larger than the grid spacing in the interior of the flow. The DES-3D model is validated using Acoustic Doppler Current Profiler flow measurements taken during the 2008 controlled flood release from Glen Canyon Dam. A point-to-point validation using a number of skill metrics, often employed in hydrological research, is proposed here for fluvial modeling. The validation results show predictive capabilities of the DES model. The model reproduces the pattern and magnitude of the velocity in the lateral recirculation zone, including the size and position of the primary and secondary eddy cells, and return current. The lateral recirculation zone is open, having continuous import of fluid upstream of the point of reattachment and export by the recirculation return current downstream of the point of separation. Differences in magnitude and direction of near-bed and near-surface velocity vectors are found, resulting in an inward vertical spiral. Interaction between the recirculation return current and the main flow is dynamic, with large temporal changes in flow direction and magnitude. Turbulence structures with a predominately vertical axis of vorticity are observed in the shear layer becoming three-dimensional without preferred orientation downstream.
AB - Lateral flow separation occurs in rivers where banks exhibit strong curvature. In canyon-bound rivers, lateral recirculation zones are the principal storage of fine-sediment deposits. A parallelized, three-dimensional, turbulence-resolving model was developed to study the flow structures along lateral separation zones located in two pools along the Colorado River in Marble Canyon. The model employs the detached eddy simulation (DES) technique, which resolves turbulence structures larger than the grid spacing in the interior of the flow. The DES-3D model is validated using Acoustic Doppler Current Profiler flow measurements taken during the 2008 controlled flood release from Glen Canyon Dam. A point-to-point validation using a number of skill metrics, often employed in hydrological research, is proposed here for fluvial modeling. The validation results show predictive capabilities of the DES model. The model reproduces the pattern and magnitude of the velocity in the lateral recirculation zone, including the size and position of the primary and secondary eddy cells, and return current. The lateral recirculation zone is open, having continuous import of fluid upstream of the point of reattachment and export by the recirculation return current downstream of the point of separation. Differences in magnitude and direction of near-bed and near-surface velocity vectors are found, resulting in an inward vertical spiral. Interaction between the recirculation return current and the main flow is dynamic, with large temporal changes in flow direction and magnitude. Turbulence structures with a predominately vertical axis of vorticity are observed in the shear layer becoming three-dimensional without preferred orientation downstream.
KW - Colorado River
KW - Dettached Eddy Simulation
KW - Fluvial Geomorphology
KW - Large Eddy Simulation
KW - Rivers
KW - Three-dimensional Model
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U2 - 10.1002/2016JF003895
DO - 10.1002/2016JF003895
M3 - Article
AN - SCOPUS:85007564440
SN - 2169-9003
VL - 122
SP - 25
EP - 49
JO - Journal of Geophysical Research: Earth Surface
JF - Journal of Geophysical Research: Earth Surface
IS - 1
ER -