{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:61990"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:61990","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Mikroelektrochemische Quantifizierung von Strömungsintensitäten zum Studium der Wirksamkeit von wandreibungsvermindernden Additiven","abstract":"The momentum transfer intensity of flowing liquid with solid walls determines the flow resistance (wall friction), heat tranfer, mass transfer, and also the likelihood of erosion corrosion initiation on solid surfaces, and is generally characterized in terms of wall shear stresses as an integral parameter. By comparing the order of magnitude of wall shear stresses encoutered in real flow systems (1 to serveral hunderts Pa in extreme cases) with the fracture stress and adhesion forces of corrosion product layers (carbonates, sulfides, oxides) ranging in the Megapascal order it appears that wall shear stresses are orders of magnitudes too small to be directly responsible for the destruction of protective scales. In this thesis microelectrochemical current noise analysis of near-wall flow dynamics under impinging jet conditions using wavelet transform indicated for the first time that the maximum interaction energy between near-wall microturbulences and the solid wall can range several orders of magnitude higher than derived from wall shear stress data and is based on the same effects that produce 'freak waves' at the water-air interface. It is long known that the wall shear stress can be considerably reduced by small concentrations of macromolecular compounds and/or substances with potential for supramolecular aggregation (micelle formers). The near-wall freak wave intensity affecting the flow dynamics in the viscous sublayer can be damped significantly by adding surface active compounds at concentrations above the critical micelle concentration. In case of the best additive tested, the maximum transfer Energy can be lowered under the adhesion forces of corrosion product layers. This effect was proofed in corrosion experiment. These findings shed new light on the interactions of flowing fluids with walls and the significant effects supramolecular structures can exert in nanoscale distances from the wall. In order to favour wall interaction effects, exploratory investigations have been performed with microchannels [47] using Si planar technology microelectrode arrays positioned at the bottom of small channels (1000 x 1000 µm, 100 x 1000 µm, 500 x 500 µm) produced in Forturanä glass technology. Surprisingly, compounds active in (electrochemically indicated) near-wall freak wave damping in macro systems appear ineffective in microchannel. While more detailed mechanistic and molecular kinetic evaluation of the data is still needed together with systematic structure-efficiency investigations, the new results outlined above clearly indicate that the cosen methodology (electrochemical quantification of flow intensities with microelectrode arrays in micro-flow channels), the data aquisition rate (200 kHz) and the data evaluation (current noise analysis via wavelet transform with subsequent calculation of near-wall freak wave intensities) represent an efficient approach to study the effect of supramolecular structure in flow fields in nanoscaled distances from the interface.","abstract_html":"The momentum transfer intensity of flowing liquid with solid walls determines the flow resistance (wall friction), heat tranfer, mass transfer, and also the likelihood of erosion corrosion initiation on solid surfaces, and is generally characterized in terms of wall shear stresses as an integral parameter. By comparing the order of magnitude of wall shear stresses encoutered in real flow systems (1 to serveral hunderts Pa in extreme cases) with the fracture stress and adhesion forces of corrosion product layers (carbonates, sulfides, oxides) ranging in the Megapascal order it appears that wall shear stresses are orders of magnitudes too small to be directly responsible for the destruction of protective scales. In this thesis microelectrochemical current noise analysis of near-wall flow dynamics under impinging jet conditions using wavelet transform indicated for the first time that the maximum interaction energy between near-wall microturbulences and the solid wall can range several orders of magnitude higher than derived from wall shear stress data and is based on the same effects that produce 'freak waves' at the water-air interface. It is long known that the wall shear stress can be considerably reduced by small concentrations of macromolecular compounds and/or substances with potential for supramolecular aggregation (micelle formers). The near-wall freak wave intensity affecting the flow dynamics in the viscous sublayer can be damped significantly by adding surface active compounds at concentrations above the critical micelle concentration. In case of the best additive tested, the maximum transfer Energy can be lowered under the adhesion forces of corrosion product layers. This effect was proofed in corrosion experiment. These findings shed new light on the interactions of flowing fluids with walls and the significant effects supramolecular structures can exert in nanoscale distances from the wall. In order to favour wall interaction effects, exploratory investigations have been performed with microchannels [47] using Si planar technology microelectrode arrays positioned at the bottom of small channels (1000 x 1000 µm, 100 x 1000 µm, 500 x 500 µm) produced in Forturanä glass technology. Surprisingly, compounds active in (electrochemically indicated) near-wall freak wave damping in macro systems appear ineffective in microchannel. While more detailed mechanistic and molecular kinetic evaluation of the data is still needed together with systematic structure-efficiency investigations, the new results outlined above clearly indicate that the cosen methodology (electrochemical quantification of flow intensities with microelectrode arrays in micro-flow channels), the data aquisition rate (200 kHz) and the data evaluation (current noise analysis via wavelet transform with subsequent calculation of near-wall freak wave intensities) represent an efficient approach to study the effect of supramolecular structure in flow fields in nanoscaled distances from the interface.","abstract_has_math":false,"creators":["Werner, Christoph"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Schmitt, Günter"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2003,"date_issued":"2003","date_published":"2003","updated_at":"2026-07-30T19:43:19Z","subjects":["info:eu-repo/classification/ddc/620","Fluid","Wandschubspannung","Elektrochemische Messung","Sensor-Array","Siliciumsensor","Mikroelektrode","Additiv","Erosionsverschleiß","Mathematisches Modell","Ingenieurwissenschaften","Mikroelektrochemie","Mikroelektroden","Erosionskorrosion","lokale Strömungsintensitäten","viskose Unterschicht","Wandreibung"],"languages":["ger"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123591%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123591%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123591%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/61990","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Schmitt, Günter"]},{"key":"dc:creator","label":"Author","values":["Werner, Christoph"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2003"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-7787","info:eu-repo/semantics/altIdentifier/doi/10.18154/RWTH-CONV-123591"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/620","Fluid","Wandschubspannung","Elektrochemische Messung","Sensor-Array","Siliciumsensor","Mikroelektrode","Additiv","Erosionsverschleiß","Mathematisches Modell","Ingenieurwissenschaften","Mikroelektrochemie","Mikroelektroden","Erosionskorrosion","lokale Strömungsintensitäten","viskose Unterschicht","Wandreibung"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["ger"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/61990","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123591%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The momentum transfer intensity of flowing liquid with solid walls determines the flow resistance (wall friction), heat tranfer, mass transfer, and also the likelihood of erosion corrosion initiation on solid surfaces, and is generally characterized in terms of wall shear stresses as an integral parameter. By comparing the order of magnitude of wall shear stresses encoutered in real flow systems (1 to serveral hunderts Pa in extreme cases) with the fracture stress and adhesion forces of corrosion product layers (carbonates, sulfides, oxides) ranging in the Megapascal order it appears that wall shear stresses are orders of magnitudes too small to be directly responsible for the destruction of protective scales. In this thesis microelectrochemical current noise analysis of near-wall flow dynamics under impinging jet conditions using wavelet transform indicated for the first time that the maximum interaction energy between near-wall microturbulences and the solid wall can range several orders of magnitude higher than derived from wall shear stress data and is based on the same effects that produce 'freak waves' at the water-air interface. It is long known that the wall shear stress can be considerably reduced by small concentrations of macromolecular compounds and/or substances with potential for supramolecular aggregation (micelle formers). The near-wall freak wave intensity affecting the flow dynamics in the viscous sublayer can be damped significantly by adding surface active compounds at concentrations above the critical micelle concentration. In case of the best additive tested, the maximum transfer Energy can be lowered under the adhesion forces of corrosion product layers. This effect was proofed in corrosion experiment. These findings shed new light on the interactions of flowing fluids with walls and the significant effects supramolecular structures can exert in nanoscale distances from the wall. In order to favour wall interaction effects, exploratory investigations have been performed with microchannels [47] using Si planar technology microelectrode arrays positioned at the bottom of small channels (1000 x 1000 µm, 100 x 1000 µm, 500 x 500 µm) produced in Forturanä glass technology. Surprisingly, compounds active in (electrochemically indicated) near-wall freak wave damping in macro systems appear ineffective in microchannel. While more detailed mechanistic and molecular kinetic evaluation of the data is still needed together with systematic structure-efficiency investigations, the new results outlined above clearly indicate that the cosen methodology (electrochemical quantification of flow intensities with microelectrode arrays in micro-flow channels), the data aquisition rate (200 kHz) and the data evaluation (current noise analysis via wavelet transform with subsequent calculation of near-wall freak wave intensities) represent an efficient approach to study the effect of supramolecular structure in flow fields in nanoscaled distances from the interface."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University IV, 150 S. Ill., graph. Darst. (2003). doi:10.18154/RWTH-CONV-123591 = Aachen, Techn. 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By comparing the order of magnitude of wall shear stresses encoutered in real flow systems (1 to serveral hunderts Pa in extreme cases) with the fracture stress and adhesion forces of corrosion product layers (carbonates, sulfides, oxides) ranging in the Megapascal order it appears that wall shear stresses are orders of magnitudes too small to be directly responsible for the destruction of protective scales. In this thesis microelectrochemical current noise analysis of near-wall flow dynamics under impinging jet conditions using wavelet transform indicated for the first time that the maximum interaction energy between near-wall microturbulences and the solid wall can range several orders of magnitude higher than derived from wall shear stress data and is based on the same effects that produce 'freak waves' at the water-air interface. It is long known that the wall shear stress can be considerably reduced by small concentrations of macromolecular compounds and/or substances with potential for supramolecular aggregation (micelle formers). The near-wall freak wave intensity affecting the flow dynamics in the viscous sublayer can be damped significantly by adding surface active compounds at concentrations above the critical micelle concentration. In case of the best additive tested, the maximum transfer Energy can be lowered under the adhesion forces of corrosion product layers. This effect was proofed in corrosion experiment. These findings shed new light on the interactions of flowing fluids with walls and the significant effects supramolecular structures can exert in nanoscale distances from the wall. In order to favour wall interaction effects, exploratory investigations have been performed with microchannels [47] using Si planar technology microelectrode arrays positioned at the bottom of small channels (1000 x 1000 µm, 100 x 1000 µm, 500 x 500 µm) produced in Forturanä glass technology. Surprisingly, compounds active in (electrochemically indicated) near-wall freak wave damping in macro systems appear ineffective in microchannel. While more detailed mechanistic and molecular kinetic evaluation of the data is still needed together with systematic structure-efficiency investigations, the new results outlined above clearly indicate that the cosen methodology (electrochemical quantification of flow intensities with microelectrode arrays in micro-flow channels), the data aquisition rate (200 kHz) and the data evaluation (current noise analysis via wavelet transform with subsequent calculation of near-wall freak wave intensities) represent an efficient approach to study the effect of supramolecular structure in flow fields in nanoscaled distances from the interface."],"dc:identifier":["https://publications.rwth-aachen.de/record/61990","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123591%22"],"dc:language":["ger"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-7787","info:eu-repo/semantics/altIdentifier/doi/10.18154/RWTH-CONV-123591"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University IV, 150 S. 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