scispace - formally typeset
Search or ask a question
Author

David Sumner

Bio: David Sumner is an academic researcher from University of Saskatchewan. The author has contributed to research in topics: Reynolds number & Vortex. The author has an hindex of 23, co-authored 82 publications receiving 2769 citations. Previous affiliations of David Sumner include University of Waterloo & McGill University.


Papers
More filters
Journal ArticleDOI
TL;DR: The current understanding of the flow around two infinite circular cylinders of equal diameter immersed in a steady cross-flow, with a focus on the near-wake flow patterns, Reynolds number effects, intermediate wake structure and behaviour, and the general trends in the measurements of the aerodynamic force coefficients and Strouhal numbers are reviewed in this paper.

630 citations

Journal ArticleDOI
TL;DR: In this paper, the flow field for two and three circular cylinders of equal diameter D arranged in a side-by-side configuration in steady crossflow was investigated using flow visualization, hot-film anemometry and particle image velocimetry (PIV), for centre-to-centre pitch ratios from T / D = 1·0 to 6·0, and Reynolds numbers from Re=500 to 3000.

327 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used flow visualization and particle image velocimetry to investigate the flow around two circular cylinders of equal diameter arranged in a staggered configuration, and found that vortex shedding frequencies are more properly associated with individual shear layers than with individual cylinders.
Abstract: The flow around two circular cylinders of equal diameter, arranged in a staggered configuration, was investigated using flow visualization and particle image velocimetry for centre-to-centre pitch ratio P/D = 1[ratio ]0 to 5.0 and angle of incidence. α = 0° to 90°. Experiments were conducted within the low subcritical Reynolds number regime, from Re = 850 to 1900. Nine flow patterns were identified, and processes of shear layer reattachment, induced separation, vortex pairing and synchronization, and vortex impingement, were observed. New insight was gained into previously published Strouhal number data, by considering the flow patterns involved. The study revealed that vortex shedding frequencies are more properly associated with individual shear layers than with individual cylinders; more specifically, the two shear layers from the downstream cylinder often shed vortices at different frequencies.

327 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the wake of a finite circular cylinder of small aspect ratio with a seven-hole probe and thermal anemometry, which was mounted normal to a ground plane and was partially immersed in a turbulent boundary layer.
Abstract: The wake of a finite circular cylinder of small aspect ratio was studied with a seven-hole probe and thermal anemometry. The cylinder was mounted normal to a ground plane and was partially immersed in a turbulent boundary layer. The time-averaged velocity and streamwise vorticity fields showed the development of the tip vortex structures, the extent of the near-wake recirculation zone, the downwash phenomenon and base vortex structures within the boundary layer. The wake structure and power spectra were similar for cylinder aspect ratios of 5 to 9, but a distinctly different behaviour was observed for an aspect ratio of 3.

296 citations

Journal ArticleDOI
TL;DR: In this article, the effect of changing the gap between the cylinder and the wall, from G = 0 (cylinder touching the wall) to G / D = 2, was investigated and it was shown that the flow may be characterized by four distinct regions.

242 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, a sparsity-promoting variant of the standard dynamic mode decomposition (DMD) algorithm is developed, where sparsity is induced by regularizing the least-squares deviation between the matrix of snapshots and the linear combination of DMD modes with an additional term that penalizes the l 1-norm of the vector of the DMD amplitudes.
Abstract: Dynamic mode decomposition (DMD) represents an effective means for capturing the essential features of numerically or experimentally generated flow fields. In order to achieve a desirable tradeoff between the quality of approximation and the number of modes that are used to approximate the given fields, we develop a sparsity-promoting variant of the standard DMD algorithm. Sparsity is induced by regularizing the least-squares deviation between the matrix of snapshots and the linear combination of DMD modes with an additional term that penalizes the l1-norm of the vector of DMD amplitudes. The globally optimal solution of the resulting regularized convex optimization problem is computed using the alternating direction method of multipliers, an algorithm well-suited for large problems. Several examples of flow fields resulting from numerical simulations and physical experiments are used to illustrate the effectiveness of the developed method.

678 citations

Journal ArticleDOI
TL;DR: The current understanding of the flow around two infinite circular cylinders of equal diameter immersed in a steady cross-flow, with a focus on the near-wake flow patterns, Reynolds number effects, intermediate wake structure and behaviour, and the general trends in the measurements of the aerodynamic force coefficients and Strouhal numbers are reviewed in this paper.

630 citations

Journal ArticleDOI
TL;DR: In this paper, a selective review of recent research on vortex-induced vibrations of isolated circular cylinders and the flow and vibration of circular cylinders in a tandem arrangement is presented, a common thread being that the topics raised are of particular interest to the author.

568 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used flow visualization and particle image velocimetry to investigate the flow around two circular cylinders of equal diameter arranged in a staggered configuration, and found that vortex shedding frequencies are more properly associated with individual shear layers than with individual cylinders.
Abstract: The flow around two circular cylinders of equal diameter, arranged in a staggered configuration, was investigated using flow visualization and particle image velocimetry for centre-to-centre pitch ratio P/D = 1[ratio ]0 to 5.0 and angle of incidence. α = 0° to 90°. Experiments were conducted within the low subcritical Reynolds number regime, from Re = 850 to 1900. Nine flow patterns were identified, and processes of shear layer reattachment, induced separation, vortex pairing and synchronization, and vortex impingement, were observed. New insight was gained into previously published Strouhal number data, by considering the flow patterns involved. The study revealed that vortex shedding frequencies are more properly associated with individual shear layers than with individual cylinders; more specifically, the two shear layers from the downstream cylinder often shed vortices at different frequencies.

327 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the wake of a finite circular cylinder of small aspect ratio with a seven-hole probe and thermal anemometry, which was mounted normal to a ground plane and was partially immersed in a turbulent boundary layer.
Abstract: The wake of a finite circular cylinder of small aspect ratio was studied with a seven-hole probe and thermal anemometry. The cylinder was mounted normal to a ground plane and was partially immersed in a turbulent boundary layer. The time-averaged velocity and streamwise vorticity fields showed the development of the tip vortex structures, the extent of the near-wake recirculation zone, the downwash phenomenon and base vortex structures within the boundary layer. The wake structure and power spectra were similar for cylinder aspect ratios of 5 to 9, but a distinctly different behaviour was observed for an aspect ratio of 3.

296 citations