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Observations of vertical structures and bedform evolution with field-scale oscillatory hydrodynamic forcing

Nichols, Claire Suzanne
http://rave.ohiolink.edu/etdc/view?acc_num=osu1203360725

Abstract Details

2008, Master of Science, Ohio State University, Civil Engineering.
Observations of the two-dimensional, time-varying velocity field were obtained with a submersible Particle Image Velocimetry (PIV) system in a field-scale, experimental environment at the O. H. Hinsdale Wave Research Laboratory. The observations were obtained over an irregularly rippled bed with ripple heights and wavelengths of roughly 1 cm and 10 cm, respectively. These observations provide the means for new insight on the interaction between fluid flow and bedform geometry near and within the wave bottom boundary layer. First, vortical structures are identified with a measure of the flow field that estimates the time for a complete revolution of a vortex, called swirling strength, allowing for the examination of the generation and ejection of individual vortical structures. An analysis of these structures reveals that the swirling strength non-dimensionalized by the wave period is correlated to the Keulegan-Carpenter number. Second, bedform evolution regimes are identified using measures of the non-dimensional bed stress (the grain roughness Shields parameter), the non-dimensional pressure gradient (the Sleath parameter), and the ripple amplitude (the ripple radius of curvature). Bedforms were found to respond to individual waves by modulating in ripple amplitude as wave groups passed, even when the Shields parameter exceeded the critical value for sheet flow. However, when the Sleath parameter exceeded the critical value for plug flow, the bedform profile flattened requiring time after the wave group passed to rebuild the ripples.
Diane Foster (Advisor)
Keith Bedford (Committee Member)
Tom Lippmann (Committee Member)
111 p.
Civil Engineering; Engineering
vortex strucures; bedform evolution, field scale, oscillatory

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Citations

  • Nichols, C. S. (2008). Observations of vertical structures and bedform evolution with field-scale oscillatory hydrodynamic forcing [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1203360725

    APA Style (7th edition)

  • Nichols, Claire. Observations of vertical structures and bedform evolution with field-scale oscillatory hydrodynamic forcing. 2008. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1203360725.

    MLA Style (8th edition)

  • Nichols, Claire. "Observations of vertical structures and bedform evolution with field-scale oscillatory hydrodynamic forcing." Master's thesis, Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1203360725

    Chicago Manual of Style (17th edition)

osu1203360725
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© 2008, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.