Effects of Spacing and Geometry of Distributed Roughness Elements on a Two-Dimensional Turbulent Boundary Layer

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dc.contributor.authorStewart, Devin O.en
dc.contributor.committeechairSimpson, Roger L.en
dc.contributor.committeememberDevenport, William J.en
dc.contributor.committeememberNeu, Wayne L.en
dc.contributor.departmentAerospace and Ocean Engineeringen
dc.date.accessioned2014-03-14T20:47:01Zen
dc.date.adate2005-12-09en
dc.date.available2014-03-14T20:47:01Zen
dc.date.issued2005-08-26en
dc.date.rdate2006-12-09en
dc.date.sdate2005-10-24en
dc.description.abstractThis thesis is a study of the effects of distributed roughness elements on a two-dimensional turbulent boundary layer. Measurements were taken on a total of ten rough wall configurations: four involving Gaussian spikes, and six with circular cylindrical posts. Rough wall flows are particularly suited to study with Laser Doppler Velocimetry (LDV) due to the fact that measurements are required near a solid surface, as well has in highly turbulent fluid. The LDV system used in this study is a fine resolution (~50 micron), three-component, fiber optic system. All mean velocities, Reynolds stresses, and triple products are measured. This study is unique in the range and variety of roughness cases for which data was taken. The data show that the flow over a rough wall is characterized by high levels of turbulence near the roughness element peaks at the interface between low-speed, near-wall fluid and the higher speed fluid above. Behind an element, high-momentum fluid sweeps toward the wall, and there is a small region of ejection of low-momentum fluid. Cylindrical elements typically have larger magnitudes of turbulent stresses at their peaks compared to Gaussian elements. Trends in mean velocity profile parameters such as displacement height, roughness effect, and wake parameter are examined with respect to roughness element geometry and spacing.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-10242005-163736en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10242005-163736/en
dc.identifier.urihttp://hdl.handle.net/10919/35481en
dc.publisherVirginia Techen
dc.relation.haspartStewartMSThesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectDistributed roughnessen
dc.subjectTriple productsen
dc.subjectNear-wall flow structureen
dc.subjectReynolds stressesen
dc.subjectLaser Doppler Velocimetryen
dc.subjectTurbulent boundary layeren
dc.titleEffects of Spacing and Geometry of Distributed Roughness Elements on a Two-Dimensional Turbulent Boundary Layeren
dc.typeThesisen
thesis.degree.disciplineAerospace and Ocean Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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