{"id":{"repo_id":"whiterose","oai_identifier":"oai:etheses.whiterose.ac.uk:692"},"canonical_url":"https://search.dev.ndltd.org/etd/whiterose/oai:etheses.whiterose.ac.uk:692","repository":{"repo_id":"whiterose","name":"White Rose University Consortium","base_url":"https://etheses.whiterose.ac.uk/cgi/oai2"},"display":{"title":"An experimental investigation of roll coating phenomena","abstract":"This thesis gives an account of an extensive experimental investigation of the operation of a twin roll coater. Two distinct modes of operation are identified: Classical (fullyflooded inlet) and Meniscus (ultra-starved inlet). The former has been the subject of investigation for a number of years; the latter is less well known and would appear to have escaped the attention of the Coating Community at large prior to the research work reported here being carried out. A detailed description of how the key features of an industrial roll coater can be reproduced using a piece of simple but well designed experimental apparatus, which encapsulates all the necessary elements for an in-depth study of the flow, is presented. Various methods are used to visualise the flow. These include dye injection and novel computerised particle tracking techniques, coupled with state-of-the-art image processing and High Speed Video photography. Experiments reveal that the flow associated with the Classical mode of operation is essentially one-dimensional throughout the nip; Meniscus coating flow, on the other hand, is uniquely two-dimensional, containing large vortical structures. Also the pressure distributions are found to be quite distinct. A fully-flooded nip results in a pressure profile which exhibits a characteristic maximum and minimum, while an ultra-starved nip produces one which is linear and entirely sub-ambient. The transformation of the flow from one mode of operation to the other is then considered, a key feature of which is the behaviour of the upstream free surface which movesin to a minimum point and then out again as the flux is reduced, giving a non-singular result, that is, there are two non-dimensional values of the flux for each free surface position. Finally, the subject of instability in roll coating is addressed, for both the Classical and Meniscus regimes. A number of new instabilities were observed using High Speed Video photography and tentative explanations for their occurrence are given.","abstract_html":"This thesis gives an account of an extensive experimental investigation of the operation of a twin roll coater. Two distinct modes of operation are identified: Classical (fullyflooded inlet) and Meniscus (ultra-starved inlet). The former has been the subject of investigation for a number of years; the latter is less well known and would appear to have escaped the attention of the Coating Community at large prior to the research work reported here being carried out. A detailed description of how the key features of an industrial roll coater can be reproduced using a piece of simple but well designed experimental apparatus, which encapsulates all the necessary elements for an in-depth study of the flow, is presented. Various methods are used to visualise the flow. These include dye injection and novel computerised particle tracking techniques, coupled with state-of-the-art image processing and High Speed Video photography. Experiments reveal that the flow associated with the Classical mode of operation is essentially one-dimensional throughout the nip; Meniscus coating flow, on the other hand, is uniquely two-dimensional, containing large vortical structures. Also the pressure distributions are found to be quite distinct. A fully-flooded nip results in a pressure profile which exhibits a characteristic maximum and minimum, while an ultra-starved nip produces one which is linear and entirely sub-ambient. The transformation of the flow from one mode of operation to the other is then considered, a key feature of which is the behaviour of the upstream free surface which movesin to a minimum point and then out again as the flux is reduced, giving a non-singular result, that is, there are two non-dimensional values of the flux for each free surface position. Finally, the subject of instability in roll coating is addressed, for both the Classical and Meniscus regimes. A number of new instabilities were observed using High Speed Video photography and tentative explanations for their occurrence are given.","abstract_has_math":false,"creators":["Malone, Barry"],"institution":"University of Leeds","degree_name":"Ph.D","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Gaskell, P.H.","Savage, M.D."],"committee_chairs":[],"committee_members":[],"year":1992,"date_issued":"1992","date_published":"1992","updated_at":"2026-07-24T06:03:29Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["uk.bl.ethos.444978"],"render_values":[{"text":"uk.bl.ethos.444978","href":null,"code":true}]}]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Gaskell, P.H.","Savage, M.D."]},{"key":"dc:creator","label":"Author","values":["Malone, Barry"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1992"]},{"key":"dc:date.issued","label":"Date","values":["1992"]},{"key":"dc:publisher.commercial","label":"Dc Publisher Commercial","values":["University of Leeds"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Mechanical Engineering (Leeds)"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Leeds"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://etheses.whiterose.ac.uk/id/eprint/692/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["uk.bl.ethos.444978"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://etheses.whiterose.ac.uk/id/eprint/692/1/uk_bl_ethos_444978.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis gives an account of an extensive experimental investigation of the operation of a twin roll coater. Two distinct modes of operation are identified: Classical (fullyflooded inlet) and Meniscus (ultra-starved inlet). The former has been the subject of investigation for a number of years; the latter is less well known and would appear to have escaped the attention of the Coating Community at large prior to the research work reported here being carried out. A detailed description of how the key features of an industrial roll coater can be reproduced using a piece of simple but well designed experimental apparatus, which encapsulates all the necessary elements for an in-depth study of the flow, is presented. Various methods are used to visualise the flow. These include dye injection and novel computerised particle tracking techniques, coupled with state-of-the-art image processing and High Speed Video photography. Experiments reveal that the flow associated with the Classical mode of operation is essentially one-dimensional throughout the nip; Meniscus coating flow, on the other hand, is uniquely two-dimensional, containing large vortical structures. Also the pressure distributions are found to be quite distinct. A fully-flooded nip results in a pressure profile which exhibits a characteristic maximum and minimum, while an ultra-starved nip produces one which is linear and entirely sub-ambient. The transformation of the flow from one mode of operation to the other is then considered, a key feature of which is the behaviour of the upstream free surface which movesin to a minimum point and then out again as the flux is reduced, giving a non-singular result, that is, there are two non-dimensional values of the flux for each free surface position. Finally, the subject of instability in roll coating is addressed, for both the Classical and Meniscus regimes. A number of new instabilities were observed using High Speed Video photography and tentative explanations for their occurrence are given."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["An experimental investigation of roll coating phenomena"]}]}],"canonical_facts":{"dc:contributor.advisor":["Gaskell, P.H.","Savage, M.D."],"dc:creator":["Malone, Barry"],"dc:date":["1992"],"dc:date.issued":["1992"],"dc:description.abstract":["This thesis gives an account of an extensive experimental investigation of the operation of a twin roll coater. Two distinct modes of operation are identified: Classical (fullyflooded inlet) and Meniscus (ultra-starved inlet). The former has been the subject of investigation for a number of years; the latter is less well known and would appear to have escaped the attention of the Coating Community at large prior to the research work reported here being carried out. A detailed description of how the key features of an industrial roll coater can be reproduced using a piece of simple but well designed experimental apparatus, which encapsulates all the necessary elements for an in-depth study of the flow, is presented. Various methods are used to visualise the flow. These include dye injection and novel computerised particle tracking techniques, coupled with state-of-the-art image processing and High Speed Video photography. Experiments reveal that the flow associated with the Classical mode of operation is essentially one-dimensional throughout the nip; Meniscus coating flow, on the other hand, is uniquely two-dimensional, containing large vortical structures. Also the pressure distributions are found to be quite distinct. A fully-flooded nip results in a pressure profile which exhibits a characteristic maximum and minimum, while an ultra-starved nip produces one which is linear and entirely sub-ambient. The transformation of the flow from one mode of operation to the other is then considered, a key feature of which is the behaviour of the upstream free surface which movesin to a minimum point and then out again as the flux is reduced, giving a non-singular result, that is, there are two non-dimensional values of the flux for each free surface position. Finally, the subject of instability in roll coating is addressed, for both the Classical and Meniscus regimes. 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