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dc.contributor.authorBalakrishnan, Mahalingam IIIen_US
dc.date.accessioned2014-03-14T20:22:37Z
dc.date.available2014-03-14T20:22:37Z
dc.date.issued1997-08-28en_US
dc.identifier.otheretd-82697-195326en_US
dc.identifier.urihttp://hdl.handle.net/10919/30732
dc.description.abstractIncipient motion criterion in sediment transport is very important, as it defines the flow condition that initiates sediment motion, and is also frequently employed in models to predict the sediment transport at higher flow conditions as well. In turbulent flows, even a reasonably accurate definition of incipient motion condition becomes very difficult due to the random nature of the turbulent process, which is responsible for sediment motion under incipient conditions. This work investigates two aspects, both of which apply to incipient sediment transport conditions. The first one deals with the role of turbulence in initiating sediment motion. The second part deals with the nature of sediment-fluid interaction for more general and complex flows where the number of sediment particles that form the rough surface is varied. The first part of this work that investigates the role of turbulence in initiating sediment motion, uses a video camera to simultaneously monitor and record the sediment (glass ball) motion and corresponding fluid velocity events measured by a three-component laser Doppler Velocimeter (LDV). The results of the single ball experiment revealed that the number of LDV flow measurements increase dramatically (more than four folds) just prior to the ball motion. The fluid mean velocity and its root-mean-square (rms) values also are significantly higher than the values that correspond to the flow conditions that yield no ball motion. The second part of the work, investigation of the fluid-sediment interaction, includes five tests with varying number of sediment particles. In order to understand the nature and extent of fluid-solid interaction, velocity profile measurements using the 3-D laser system were carried out at three locations for each of these five cases. Plots of mean velocities, rms quantities located the universal layer at about 1.5 ball diameters above the porous bed. However, at higher sediment particle concentrations, this distance reduced and the beginning of the universal layer approached the top of the porous bed.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartthesis.PDFen_US
dc.rightsI hereby grant to Virginia Tech or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.en_US
dc.subjectIncipient Sediment Motionen_US
dc.subjectOpen-Channel Flowen_US
dc.subjectRoughness Sublayeren_US
dc.titleThe Role of Turbulence on the Entrainment of a Single Sphere and the Effects of Roughness on Fluid-Solid Interactionen_US
dc.typeDissertationen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMechanical Engineeringen_US
dc.contributor.committeechairDancey, Clinton L.en_US
dc.contributor.committeememberDiplas, Panayiotisen_US
dc.contributor.committeememberBrown, Eugene F.en_US
dc.contributor.committeememberPierce, Felix J.en_US
dc.contributor.committeememberNg, Wing Faien_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-82697-195326/en_US
dc.date.sdate1997-08-28en_US
dc.date.rdate1998-10-01
dc.date.adate1997-10-01en_US


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