{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/87693"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/87693","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Experimental Investigation of Acceleration and Velocity Fields in Turbulent Channel Flow","abstract":"The velocity time derivatives are associated predominantly with small scales in both space and time. Examination of instantaneous and estimates of the conditionally averaged velocity time-derivative fields indicates that the smaller-scale vortices leave a convective imprint upon the time derivatives. Further, the streamwise spectra of the velocity time-derivative support the notion that convective effects dominate the smaller scales of the flow. Comparison between the bulk convective-derivative and time-derivative spectra illustrate this behavior. At low wavenumbers, the bulk convective-derivative and time-derivative spectra coincide with one another, implying that the larger scales are dominated by evolution. At moderate wavenumbers (coincident with the streamwise spacing of the vortices associated with the outer-layer vortex organization noted earlier), the energy associated with convection reaches a maximum. With increasing Reynolds number, the influence of convective effects diminishes at all wavenumbers in terms of its contribution to the energy of the velocity time derivative. This behavior is quite encouraging from the LES-modeling viewpoint, where capturing the true evolution of the flow is the main goal.","abstract_html":"The velocity time derivatives are associated predominantly with small scales in both space and time. Examination of instantaneous and estimates of the conditionally averaged velocity time-derivative fields indicates that the smaller-scale vortices leave a convective imprint upon the time derivatives. Further, the streamwise spectra of the velocity time-derivative support the notion that convective effects dominate the smaller scales of the flow. Comparison between the bulk convective-derivative and time-derivative spectra illustrate this behavior. At low wavenumbers, the bulk convective-derivative and time-derivative spectra coincide with one another, implying that the larger scales are dominated by evolution. At moderate wavenumbers (coincident with the streamwise spacing of the vortices associated with the outer-layer vortex organization noted earlier), the energy associated with convection reaches a maximum. With increasing Reynolds number, the influence of convective effects diminishes at all wavenumbers in terms of its contribution to the energy of the velocity time derivative. This behavior is quite encouraging from the LES-modeling viewpoint, where capturing the true evolution of the flow is the main goal.","abstract_has_math":false,"creators":["Christensen, Kenneth Thor"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Theoretical and Applied Mechanics","degree_department":null,"school":null,"contributors":["Adrian, Ronald J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-28T16:23:27Z","date_published":"2015-09-28T16:23:27Z","updated_at":"2026-07-22T22:26:30Z","subjects":["Engineering, Mechanical"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI3017051"],"render_values":[{"text":"(MiAaPQ)AAI3017051","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/87693","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Adrian, Ronald J."]},{"key":"dc:creator","label":"Author","values":["Christensen, Kenneth Thor"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-28T16:23:27Z","10000-01-01","2001"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Theoretical and Applied Mechanics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Mechanical"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/87693","(MiAaPQ)AAI3017051"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The velocity time derivatives are associated predominantly with small scales in both space and time. Examination of instantaneous and estimates of the conditionally averaged velocity time-derivative fields indicates that the smaller-scale vortices leave a convective imprint upon the time derivatives. Further, the streamwise spectra of the velocity time-derivative support the notion that convective effects dominate the smaller scales of the flow. Comparison between the bulk convective-derivative and time-derivative spectra illustrate this behavior. At low wavenumbers, the bulk convective-derivative and time-derivative spectra coincide with one another, implying that the larger scales are dominated by evolution. At moderate wavenumbers (coincident with the streamwise spacing of the vortices associated with the outer-layer vortex organization noted earlier), the energy associated with convection reaches a maximum. With increasing Reynolds number, the influence of convective effects diminishes at all wavenumbers in terms of its contribution to the energy of the velocity time derivative. This behavior is quite encouraging from the LES-modeling viewpoint, where capturing the true evolution of the flow is the main goal.","Made available in DSpace on 2015-09-28T16:23:27Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3017051.pdf: 11753337 bytes, checksum: d870b467bd412dcc55b1eaf00693959c (MD5) Previous issue date: 2001","Embargo set by: Seth Robbins for item 88974 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","239 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001."]},{"key":"dc:title","label":"Title","values":["Experimental Investigation of Acceleration and Velocity Fields in Turbulent Channel Flow"]}]}],"canonical_facts":{"dc:contributor":["Adrian, Ronald J."],"dc:creator":["Christensen, Kenneth Thor"],"dc:date":["2015-09-28T16:23:27Z","10000-01-01","2001"],"dc:description":["The velocity time derivatives are associated predominantly with small scales in both space and time. Examination of instantaneous and estimates of the conditionally averaged velocity time-derivative fields indicates that the smaller-scale vortices leave a convective imprint upon the time derivatives. Further, the streamwise spectra of the velocity time-derivative support the notion that convective effects dominate the smaller scales of the flow. Comparison between the bulk convective-derivative and time-derivative spectra illustrate this behavior. At low wavenumbers, the bulk convective-derivative and time-derivative spectra coincide with one another, implying that the larger scales are dominated by evolution. At moderate wavenumbers (coincident with the streamwise spacing of the vortices associated with the outer-layer vortex organization noted earlier), the energy associated with convection reaches a maximum. With increasing Reynolds number, the influence of convective effects diminishes at all wavenumbers in terms of its contribution to the energy of the velocity time derivative. 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