Secondary circulations associated with longitudinal sea-floor sediment furrows
Secondary circulations associated with longitudinal sea-floor sediment furrows
A numerical model is developed to study the turbulence-driven secondary circulations associated with longitudinal sea-floor sedimentary furrows. The non-isotropic turbulence field is simulated with a second order turbulence model in which the Reynolds stresses in the cross-sectional plane of the longitudinal flow are solved from the modelled transport equations for the stresses. A boundary-fitted non-orthogonal curvilinear coordinate transformation is introduced, mapping the cross-sectional plane of the longitudinal flow onto a rectangle. The transformed differential equations are solved numerically with a marching forward finite-difference procedure for three-dimensional boundary-layer type flows. The model is applied to flow over a bed with transversely periodic variation. Three types of beds, namely, a hydraulically smooth bed with parallel longitudinal furrows, a flat bed with longitudinal roughness stripes and a furrowed bed with rough furrow troughs, are considered. Numerical experiments are performed to investigate the effects on the secondary circulations of changes in the primary flow (velocity and flow depth) and in the bed features (shape, amplitude and severity of the transverse variation). The implications of the model results for the sediment movement associated with the furrow development are discussed. The secondary currents act to initiate furrows on the rough stripes and to maintain their further development. The secondary circulations are enhanced by increased roughness on the furrow troughs.
University of Southampton
1987
Shi, Ping
(1987)
Secondary circulations associated with longitudinal sea-floor sediment furrows.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A numerical model is developed to study the turbulence-driven secondary circulations associated with longitudinal sea-floor sedimentary furrows. The non-isotropic turbulence field is simulated with a second order turbulence model in which the Reynolds stresses in the cross-sectional plane of the longitudinal flow are solved from the modelled transport equations for the stresses. A boundary-fitted non-orthogonal curvilinear coordinate transformation is introduced, mapping the cross-sectional plane of the longitudinal flow onto a rectangle. The transformed differential equations are solved numerically with a marching forward finite-difference procedure for three-dimensional boundary-layer type flows. The model is applied to flow over a bed with transversely periodic variation. Three types of beds, namely, a hydraulically smooth bed with parallel longitudinal furrows, a flat bed with longitudinal roughness stripes and a furrowed bed with rough furrow troughs, are considered. Numerical experiments are performed to investigate the effects on the secondary circulations of changes in the primary flow (velocity and flow depth) and in the bed features (shape, amplitude and severity of the transverse variation). The implications of the model results for the sediment movement associated with the furrow development are discussed. The secondary currents act to initiate furrows on the rough stripes and to maintain their further development. The secondary circulations are enhanced by increased roughness on the furrow troughs.
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Published date: 1987
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Local EPrints ID: 461838
URI: http://eprints.soton.ac.uk/id/eprint/461838
PURE UUID: d322ffb3-54fe-4692-a323-dd05080141bc
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Date deposited: 04 Jul 2022 18:57
Last modified: 04 Jul 2022 18:57
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Author:
Ping Shi
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