{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/105045"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/105045","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Experimental investigation of the impact of the permeable layer thickness on the surface flow above and the threshold for incipient motion of submerged objects","abstract":"Previous work regarding flows over a permeable bed has confirmed that the flow characteristics deviate from those observed in impermeable rough boundary layers. However, the effect of the permeable bed thickness is not fully understood. Current models for threshold of incipient motion implicitly assume an impermeable rough bed when evaluating the fluid forces exerted on submerged objects. Natural river beds are permeable and the impact of the presence of bed permeability or the thickness of the permeable bed on the threshold for incipient motion still remain unclear. The main research questions of the systematic experimental study in this dissertation are to better understand the following: (1) How does the thickness of the permeable bed modifies the turbulent boundary layer above, specifically, the mean velocity profiles, turbulence intensities, and flow resistance? (2) How does the presence of bed permeability as well as the thickness of the permeable bed affect the threshold for incipient motion of submerged spheres and cylinders? The experiments involved two facilities: the Illinois Hyporheic Flow Facility (IHFF) and the Woods Hole Oceanographic Institute (WHOI) flume. The WHOI flume was used to address the first research question. In this set of experiments, double-averaged (temporal and spatial) velocity fields obtained from Particle Image Velocimetry (PIV) showed that the mean velocity profiles for different thickness of the permeable layer collapse to the fully-rough velocity profile when scaling the flow velocity with shear velocity and the wall-normal distance with the diameter of the marbles in the bed. The location of the peak in turbulence intensities migrates closer to the bed as the thickness of the permeable bed increases. The friction factor increases with the Reynolds number based on momentum thickness of the boundary layer and was found to be slightly larger for thicker permeable beds. Both flumes, IHFF and WHOI, were used to address the second research question. In these experiments, the threshold of incipient motion was characterized with the Shields parameter, which was estimated with upstream flow velocity measurements. A comparison of the threshold for incipient motion of objects resting on permeable and impermeable beds having the same flow-bed geometries showed larger Shields parameter required to initiate motion on a permeable bed than on an impermeable one. The increment in the critical Shields parameter was found to be associated with a decrease of the lift force exerted on the objects when resting on a permeable bed. Bed permeability of the bed in the experiments evaluating the effect of permeable bed thickness, was an order of magnitude smaller than the ones comparing permeable and impermeable beds. As a consequence, the critical Shields parameter for submerged spheres and cylinders increases with the thickness of the permeable bed but the effect was limited compared to the case with larger bed permeability.","abstract_html":"Previous work regarding flows over a permeable bed has confirmed that the flow characteristics deviate from those observed in impermeable rough boundary layers. However, the effect of the permeable bed thickness is not fully understood. Current models for threshold of incipient motion implicitly assume an impermeable rough bed when evaluating the fluid forces exerted on submerged objects. Natural river beds are permeable and the impact of the presence of bed permeability or the thickness of the permeable bed on the threshold for incipient motion still remain unclear. The main research questions of the systematic experimental study in this dissertation are to better understand the following: (1) How does the thickness of the permeable bed modifies the turbulent boundary layer above, specifically, the mean velocity profiles, turbulence intensities, and flow resistance? (2) How does the presence of bed permeability as well as the thickness of the permeable bed affect the threshold for incipient motion of submerged spheres and cylinders? The experiments involved two facilities: the Illinois Hyporheic Flow Facility (IHFF) and the Woods Hole Oceanographic Institute (WHOI) flume. The WHOI flume was used to address the first research question. In this set of experiments, double-averaged (temporal and spatial) velocity fields obtained from Particle Image Velocimetry (PIV) showed that the mean velocity profiles for different thickness of the permeable layer collapse to the fully-rough velocity profile when scaling the flow velocity with shear velocity and the wall-normal distance with the diameter of the marbles in the bed. The location of the peak in turbulence intensities migrates closer to the bed as the thickness of the permeable bed increases. The friction factor increases with the Reynolds number based on momentum thickness of the boundary layer and was found to be slightly larger for thicker permeable beds. Both flumes, IHFF and WHOI, were used to address the second research question. In these experiments, the threshold of incipient motion was characterized with the Shields parameter, which was estimated with upstream flow velocity measurements. A comparison of the threshold for incipient motion of objects resting on permeable and impermeable beds having the same flow-bed geometries showed larger Shields parameter required to initiate motion on a permeable bed than on an impermeable one. The increment in the critical Shields parameter was found to be associated with a decrease of the lift force exerted on the objects when resting on a permeable bed. Bed permeability of the bed in the experiments evaluating the effect of permeable bed thickness, was an order of magnitude smaller than the ones comparing permeable and impermeable beds. As a consequence, the critical Shields parameter for submerged spheres and cylinders increases with the thickness of the permeable bed but the effect was limited compared to the case with larger bed permeability.","abstract_has_math":false,"creators":["Wu, Heng"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Civil Engineering","degree_department":null,"school":null,"contributors":["Garcia, Marcelo H.","Landry, Blake J.","Parker, Gary","Tinoco, Rafael O.","Valocchi, Albert J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-08-23T20:35:59Z","date_published":"2019-08-23T20:35:59Z","updated_at":"2026-07-22T22:24:44Z","subjects":["Porous media, PIV, initiation of motion"],"languages":["en"],"rights":["Copyright 2019 Heng Wu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/105045","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Garcia, Marcelo H.","Landry, Blake J.","Parker, Gary","Tinoco, Rafael O.","Valocchi, Albert J."]},{"key":"dc:creator","label":"Author","values":["Wu, Heng"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-08-23T20:35:59Z","2021-08-24T09:15:24Z","2019-04-18","2019-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"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":["Porous media, PIV, initiation of motion"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Heng Wu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/105045"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Previous work regarding flows over a permeable bed has confirmed that the flow characteristics deviate from those observed in impermeable rough boundary layers. However, the effect of the permeable bed thickness is not fully understood. Current models for threshold of incipient motion implicitly assume an impermeable rough bed when evaluating the fluid forces exerted on submerged objects. Natural river beds are permeable and the impact of the presence of bed permeability or the thickness of the permeable bed on the threshold for incipient motion still remain unclear. The main research questions of the systematic experimental study in this dissertation are to better understand the following: (1) How does the thickness of the permeable bed modifies the turbulent boundary layer above, specifically, the mean velocity profiles, turbulence intensities, and flow resistance? (2) How does the presence of bed permeability as well as the thickness of the permeable bed affect the threshold for incipient motion of submerged spheres and cylinders? The experiments involved two facilities: the Illinois Hyporheic Flow Facility (IHFF) and the Woods Hole Oceanographic Institute (WHOI) flume. The WHOI flume was used to address the first research question. In this set of experiments, double-averaged (temporal and spatial) velocity fields obtained from Particle Image Velocimetry (PIV) showed that the mean velocity profiles for different thickness of the permeable layer collapse to the fully-rough velocity profile when scaling the flow velocity with shear velocity and the wall-normal distance with the diameter of the marbles in the bed. The location of the peak in turbulence intensities migrates closer to the bed as the thickness of the permeable bed increases. The friction factor increases with the Reynolds number based on momentum thickness of the boundary layer and was found to be slightly larger for thicker permeable beds. Both flumes, IHFF and WHOI, were used to address the second research question. In these experiments, the threshold of incipient motion was characterized with the Shields parameter, which was estimated with upstream flow velocity measurements. A comparison of the threshold for incipient motion of objects resting on permeable and impermeable beds having the same flow-bed geometries showed larger Shields parameter required to initiate motion on a permeable bed than on an impermeable one. The increment in the critical Shields parameter was found to be associated with a decrease of the lift force exerted on the objects when resting on a permeable bed. Bed permeability of the bed in the experiments evaluating the effect of permeable bed thickness, was an order of magnitude smaller than the ones comparing permeable and impermeable beds. As a consequence, the critical Shields parameter for submerged spheres and cylinders increases with the thickness of the permeable bed but the effect was limited compared to the case with larger bed permeability.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-05-01","The student, Heng Wu, accepted the attached license on 2019-04-17 at 11:05.","The student, Heng Wu, submitted this Dissertation for approval on 2019-04-17 at 11:14.","This Dissertation was approved for publication on 2019-04-18 at 15:29.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13688 on 2019-08-22 at 15:06:53","Made available in DSpace on 2019-08-23T20:35:59Z (GMT). No. of bitstreams: 2 WU-DISSERTATION-2019.pdf: 46078341 bytes, checksum: feb6f97a634bc1f60d0598661b06f370 (MD5) LICENSE.txt: 4204 bytes, checksum: 5aa3f8a092d753e3c0fbf6d3a70e6600 (MD5) Previous issue date: 2019-04-18","Embargo set by: Seth Robbins for item 112164 Lift date: 2021-08-23T20:36:18Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 112164 on 2021-08-24T09:15:24Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Experimental investigation of the impact of the permeable layer thickness on the surface flow above and the threshold for incipient motion of submerged objects"]}]}],"canonical_facts":{"dc:contributor":["Garcia, Marcelo H.","Landry, Blake J.","Parker, Gary","Tinoco, Rafael O.","Valocchi, Albert J."],"dc:creator":["Wu, Heng"],"dc:date":["2019-08-23T20:35:59Z","2021-08-24T09:15:24Z","2019-04-18","2019-05"],"dc:description":["Previous work regarding flows over a permeable bed has confirmed that the flow characteristics deviate from those observed in impermeable rough boundary layers. However, the effect of the permeable bed thickness is not fully understood. Current models for threshold of incipient motion implicitly assume an impermeable rough bed when evaluating the fluid forces exerted on submerged objects. Natural river beds are permeable and the impact of the presence of bed permeability or the thickness of the permeable bed on the threshold for incipient motion still remain unclear. The main research questions of the systematic experimental study in this dissertation are to better understand the following: (1) How does the thickness of the permeable bed modifies the turbulent boundary layer above, specifically, the mean velocity profiles, turbulence intensities, and flow resistance? (2) How does the presence of bed permeability as well as the thickness of the permeable bed affect the threshold for incipient motion of submerged spheres and cylinders? The experiments involved two facilities: the Illinois Hyporheic Flow Facility (IHFF) and the Woods Hole Oceanographic Institute (WHOI) flume. The WHOI flume was used to address the first research question. In this set of experiments, double-averaged (temporal and spatial) velocity fields obtained from Particle Image Velocimetry (PIV) showed that the mean velocity profiles for different thickness of the permeable layer collapse to the fully-rough velocity profile when scaling the flow velocity with shear velocity and the wall-normal distance with the diameter of the marbles in the bed. The location of the peak in turbulence intensities migrates closer to the bed as the thickness of the permeable bed increases. The friction factor increases with the Reynolds number based on momentum thickness of the boundary layer and was found to be slightly larger for thicker permeable beds. Both flumes, IHFF and WHOI, were used to address the second research question. In these experiments, the threshold of incipient motion was characterized with the Shields parameter, which was estimated with upstream flow velocity measurements. A comparison of the threshold for incipient motion of objects resting on permeable and impermeable beds having the same flow-bed geometries showed larger Shields parameter required to initiate motion on a permeable bed than on an impermeable one. The increment in the critical Shields parameter was found to be associated with a decrease of the lift force exerted on the objects when resting on a permeable bed. Bed permeability of the bed in the experiments evaluating the effect of permeable bed thickness, was an order of magnitude smaller than the ones comparing permeable and impermeable beds. As a consequence, the critical Shields parameter for submerged spheres and cylinders increases with the thickness of the permeable bed but the effect was limited compared to the case with larger bed permeability.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-05-01","The student, Heng Wu, accepted the attached license on 2019-04-17 at 11:05.","The student, Heng Wu, submitted this Dissertation for approval on 2019-04-17 at 11:14.","This Dissertation was approved for publication on 2019-04-18 at 15:29.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13688 on 2019-08-22 at 15:06:53","Made available in DSpace on 2019-08-23T20:35:59Z (GMT). No. of bitstreams: 2 WU-DISSERTATION-2019.pdf: 46078341 bytes, checksum: feb6f97a634bc1f60d0598661b06f370 (MD5) LICENSE.txt: 4204 bytes, checksum: 5aa3f8a092d753e3c0fbf6d3a70e6600 (MD5) Previous issue date: 2019-04-18","Embargo set by: Seth Robbins for item 112164 Lift date: 2021-08-23T20:36:18Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 112164 on 2021-08-24T09:15:24Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/105045"],"dc:language":["en"],"dc:rights":["Copyright 2019 Heng Wu"],"dc:subject":["Porous media, PIV, initiation of motion"],"dc:title":["Experimental investigation of the impact of the permeable layer thickness on the surface flow above and the threshold for incipient motion of submerged objects"],"dc:type":["text"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:44Z"}