Sediment resuspension and erosion by vortex rings

Munro, Richard J.; Bethke, N.; Dalziel, S. B.

Abstract

Particle resuspension and erosion induced by a vortex ringinteracting with a sediment layer was investigated experimentally using flow visualization (particle image velocimetry), high-speed video, and a recently developed light attenuation method for measuring displacements in bed level. Near-spherical sediment particles were used throughout with relative densities of 1.2–7 and diameters (d)(d) ranging between 90 and 1600 μm1600 μm. Attention was focused on initially smooth, horizontal bedforms with the vortex ring aligned to approach the bed vertically. Interaction characteristics were investigated in terms of the dimensionless Shields parameter, defined using the vortex-ring propagation speed. The critical conditions for resuspension (whereby particles are only just resuspended) were determined as a function of particle Reynolds number (based on the particle settling velocity and dd). The effects of viscous damping were found to be significant for d/δ<15d/δ<15, where δδ denotes the viscous sublayer thickness. Measurements of bed deformation were obtained during the interaction period, for a range of impact conditions. The (azimuthal) mean crater profile is shown to be generally self-similar during the interaction period, except for the most energetic impacts and larger sediment types. Loss of similarity occurs when the local bed slope approaches the repose limit, leading to collapse. Erosion, deposition, and resuspension volumes are analyzed as a function interaction time, impact condition, and sediment size.

Citation

Munro, R. J., Bethke, N., & Dalziel, S. B. (in press). Sediment resuspension and erosion by vortex rings. Physics of Fluids, 21(4), https://doi.org/10.1063/1.3083318

• Journal Article Type: Article
• Acceptance Date: Jan 26, 2009
• Online Publication Date: Apr 8, 2009
• Deposit Date: Jul 9, 2016
• Publicly Available Date: Jul 9, 2016
• Journal: Physics of Fluids
• Print ISSN: 1070-6631
• Electronic ISSN: 1089-7666
• Publisher: American Institute of Physics
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 4
• DOI: https://doi.org/10.1063/1.3083318
• Public URL: https://nottingham-repository.worktribe.com/output/705377
• Publisher URL: http://scitation.aip.org/content/aip/journal/pof2/21/4/10.1063/1.3083318
• Additional Information: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.; ; The following article appeared in Sediment resuspension and erosion by vortex rings; Munro, R. J. and Bethke, N. and Dalziel, S. B., Physics of Fluids, 21, 046601 (2009) and may be found at http://dx.doi.org/10.1063/1.3083318.
• Contract Date: Jul 9, 2016