{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/129935"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/129935","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Particle manipulation by hydrodynamic effects in vortical stokes flow","abstract":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms","abstract_html":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms","abstract_has_math":false,"creators":["Liu, Xuchen"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Hilgenfeldt, Sascha","Chamorro, Leonardo","Constante Amores, Cristian","Feng, Jie"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-07-16","date_published":"2025-07-16","updated_at":"2026-07-22T22:25:06Z","subjects":["Microfluidics","Particle/fluid Flows"],"languages":["en","eng"],"rights":["Copyright 2025 Xuchen Liu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/129935","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hilgenfeldt, Sascha","Chamorro, Leonardo","Constante Amores, Cristian","Feng, Jie"]},{"key":"dc:creator","label":"Author","values":["Liu, Xuchen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-07-16","2025-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical 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 Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Microfluidics","Particle/fluid Flows"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Xuchen Liu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/129935"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms","The student, Xuchen Liu, accepted the attached license on 2025-07-11 at 12:04.","The student, Xuchen Liu, submitted this Dissertation for approval on 2025-07-11 at 12:13.","This Dissertation was approved for publication on 2025-07-16 at 09:34.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22511 on 2025-10-20 at 20:15:10","Manipulation of small-scale particles across streamlines is the elementary task of microfluidic devices, particularly in the context of cell-sized objects in bioengineering and biomedical applications. Such particles tend to be nearly density-matched, and they have a strong tendency to follow the ambient flow passively. Particle manipulation necessitates pulling objects across streamlines; if they cannot be actuated by bulk forces (due to charges or significant gravitational forces), they must be moved by hydrodynamic forces. Many such devices operate at very low Reynolds numbers and deflect particles using arrays of obstacles; however, a systematic quantification of the relevant hydrodynamic effects has been lacking. Here, we explore an alternate approach, elucidating manipulation strategies for particles in vortical internal Stokes flows given by Moffatt’s classical, analytically known solutions. We find that even force-free spherical particles can be moved across streamlines through the hydrodynamic particle-wall interaction. By rigorously modeling the wall interactions, we show that symmetry breaking of the vortex geometry is necessary for systematic and lasting deflection of particles, revealing a surprising variety of possible strategies. Depending on the flow geometry, particles can be made to accumulate at either fixed points or limit cycles. Moreover, particles can be forced onto trajectories approaching channel walls exponentially closely, making quantitative predictions of particle capture (sticking) by short-range forces possible. This rich, particle-size-dependent behavior suggests the versatile use of inertia-less flow in devices with a long particle residence time for concentration, sorting, or filtering. Generalizing from the case of single spherical particles, we also investigate the behavior of a rigid dumbbell particle in equivalent Moffatt eddy flows, adding a rotational degree of freedom to the dynamical system describing particle motion. Surprisingly, we find that even without the effect of particle-wall interaction, a rigid dumbbell can be forced onto a predetermined limit cycle. Again, this behavior is dependent on symmetry breaking of the vortex: without breaking the symmetry, we find dumbbell orbits to be quasi-periodic. We classify and quantify these effects relative to the impact of particle-wall interactions, further enriching the toolbox of particle manipulation strategies."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Particle manipulation by hydrodynamic effects in vortical stokes flow"]}]}],"canonical_facts":{"dc:contributor":["Hilgenfeldt, Sascha","Chamorro, Leonardo","Constante Amores, Cristian","Feng, Jie"],"dc:creator":["Liu, Xuchen"],"dc:date":["2025-07-16","2025-08"],"dc:description":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms","The student, Xuchen Liu, accepted the attached license on 2025-07-11 at 12:04.","The student, Xuchen Liu, submitted this Dissertation for approval on 2025-07-11 at 12:13.","This Dissertation was approved for publication on 2025-07-16 at 09:34.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22511 on 2025-10-20 at 20:15:10","Manipulation of small-scale particles across streamlines is the elementary task of microfluidic devices, particularly in the context of cell-sized objects in bioengineering and biomedical applications. Such particles tend to be nearly density-matched, and they have a strong tendency to follow the ambient flow passively. Particle manipulation necessitates pulling objects across streamlines; if they cannot be actuated by bulk forces (due to charges or significant gravitational forces), they must be moved by hydrodynamic forces. Many such devices operate at very low Reynolds numbers and deflect particles using arrays of obstacles; however, a systematic quantification of the relevant hydrodynamic effects has been lacking. Here, we explore an alternate approach, elucidating manipulation strategies for particles in vortical internal Stokes flows given by Moffatt’s classical, analytically known solutions. We find that even force-free spherical particles can be moved across streamlines through the hydrodynamic particle-wall interaction. By rigorously modeling the wall interactions, we show that symmetry breaking of the vortex geometry is necessary for systematic and lasting deflection of particles, revealing a surprising variety of possible strategies. Depending on the flow geometry, particles can be made to accumulate at either fixed points or limit cycles. Moreover, particles can be forced onto trajectories approaching channel walls exponentially closely, making quantitative predictions of particle capture (sticking) by short-range forces possible. This rich, particle-size-dependent behavior suggests the versatile use of inertia-less flow in devices with a long particle residence time for concentration, sorting, or filtering. Generalizing from the case of single spherical particles, we also investigate the behavior of a rigid dumbbell particle in equivalent Moffatt eddy flows, adding a rotational degree of freedom to the dynamical system describing particle motion. Surprisingly, we find that even without the effect of particle-wall interaction, a rigid dumbbell can be forced onto a predetermined limit cycle. Again, this behavior is dependent on symmetry breaking of the vortex: without breaking the symmetry, we find dumbbell orbits to be quasi-periodic. We classify and quantify these effects relative to the impact of particle-wall interactions, further enriching the toolbox of particle manipulation strategies."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/129935"],"dc:language":["en","eng"],"dc:rights":["Copyright 2025 Xuchen Liu"],"dc:subject":["Microfluidics","Particle/fluid Flows"],"dc:title":["Particle manipulation by hydrodynamic effects in vortical stokes flow"],"dc:type":["text"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:06Z"}