Simultaneous measurement of 3D velocity and 2D temperature fields for unsteady thermocapillary convection in thin liquid films

Simultaneous measurement of 3D velocity and 2D temperature fields for unsteady thermocapillary convection in thin liquid films | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Simultaneous measurement of 3D velocity and 2D temperature fields for unsteady thermocapillary convection in thin liquid films Kohki Ito, Koichi Nishino, Masaki Kudo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8637363/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Thermocapillary convection driven by surface-tension gradients is an interfacial transport mechanism governing flow phenomena across a wide range of length scales, from thin liquid films to molten material processing. In crystal growth technologies, high-purity bulk single crystals are typically fabricated using the Czochralski and floating-zone methods, both of which can be adversely affected by hydrothermal waves (HTWs) arising from thermocapillary instabilities. The development of a digital twin for HTW dynamics can enable flow control and optimize crystal growth by minimizing defects. Such a framework requires three-dimensional (3D) velocity information; however, the full 3D velocity structure of HTWs has not yet been experimentally captured. The present study addresses this gap by acquiring 3D velocity fields of a fully developed HTW in a thin liquid film using tomographic stereo particle image velocimetry (TSPIV), combined with simultaneous infrared (IR) measurements of the free-surface temperature. Experiments were conducted in a rectangular container filled with silicone oil (Prandtl number 16.1), where characteristic HTW features—including roll propagation angle, roll frequency, phase velocity, and spatial wavenumber—were identified. The values obtained from TSPIV measurements show quantitative agreement with those reported in previous studies. In addition, the combined TSPIV and IR measurements captured source and suction flow structures near the free surface, revealing correspondence between temperature patterns and flow organization. These results demonstrate the feasibility of utilizing IR-based free-surface temperature data as a key component in constructing a digital twin of HTW-driven thermocapillary convection and provide experimental insights into three-dimensional flow structures relevant to high-purity crystal growth. high-purity crystals hydrothermal waves thermocapillary convection tomographic stereo particle image velocimetry infrared measurements Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 28 Feb, 2026 Reviews received at journal 28 Feb, 2026 Reviews received at journal 18 Feb, 2026 Reviewers agreed at journal 05 Feb, 2026 Reviewers agreed at journal 23 Jan, 2026 Reviewers invited by journal 23 Jan, 2026 Editor assigned by journal 20 Jan, 2026 Submission checks completed at journal 19 Jan, 2026 First submitted to journal 19 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8637363","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":579424958,"identity":"956b952d-a318-4e9a-92f9-2a1b0f1dba84","order_by":0,"name":"Kohki Ito","email":"","orcid":"","institution":"Tokyo Metropolitan College of Industrial Technology","correspondingAuthor":false,"prefix":"","firstName":"Kohki","middleName":"","lastName":"Ito","suffix":""},{"id":579424959,"identity":"44cf114d-35d2-4355-bcff-68bfa79c5c26","order_by":1,"name":"Koichi Nishino","email":"","orcid":"","institution":"Yokohama National University","correspondingAuthor":false,"prefix":"","firstName":"Koichi","middleName":"","lastName":"Nishino","suffix":""},{"id":579424960,"identity":"ebd9d32d-e140-480f-97e3-bcd87787f17b","order_by":2,"name":"Masaki Kudo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYBACCQYGA4YPMF4CCoVHC+MMMA1Sm0CkFmYemBYCiiFAckbyxse2OTZ15u0NjB8e/mCQ529gePYAnxZpibRi49xtaRIyZw4wSwAdZjjjAEO6AT4tchI5ZtK52w5LSEjkfwP5hXEDA0OaBEEtltv+A7UksIG02BPUIg3SwrjtAFxLIkEtkj3Pig17tyVLzuAB+SVNInnGYQJ+kTievPHBz212/BLsDYwff9jY2Pa396Q9wKcFwwgGBmaeNFJ0gAH7MZK1jIJRMApGwbAGAMPEPW/p3Tc2AAAAAElFTkSuQmCC","orcid":"","institution":"Tokyo Metropolitan College of Industrial Technology","correspondingAuthor":true,"prefix":"","firstName":"Masaki","middleName":"","lastName":"Kudo","suffix":""}],"badges":[],"createdAt":"2026-01-19 09:08:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8637363/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8637363/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101398580,"identity":"54d9fc71-a4e9-4f87-907f-294d8c1e8236","added_by":"auto","created_at":"2026-01-29 09:42:36","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1881766,"visible":true,"origin":"","legend":"","description":"","filename":"EiFMKudo2501191st.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8637363/v1_covered_2a63826c-6e15-4376-8030-301c14000e40.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Simultaneous measurement of 3D velocity and 2D temperature fields for unsteady thermocapillary convection in thin liquid films","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"experiments-in-fluids","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"exif","sideBox":"Learn more about [Experiments in Fluids](http://link.springer.com/journal/348)","snPcode":"348","submissionUrl":"https://submission.nature.com/new-submission/348/3","title":"Experiments in Fluids","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"high-purity crystals, hydrothermal waves, thermocapillary convection, tomographic stereo particle image velocimetry, infrared measurements","lastPublishedDoi":"10.21203/rs.3.rs-8637363/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8637363/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThermocapillary convection driven by surface-tension gradients is an interfacial transport mechanism governing flow phenomena across a wide range of length scales, from thin liquid films to molten material processing. In crystal growth technologies, high-purity bulk single crystals are typically fabricated using the Czochralski and floating-zone methods, both of which can be adversely affected by hydrothermal waves (HTWs) arising from thermocapillary instabilities. The development of a digital twin for HTW dynamics can enable flow control and optimize crystal growth by minimizing defects. Such a framework requires three-dimensional (3D) velocity information; however, the full 3D velocity structure of HTWs has not yet been experimentally captured. The present study addresses this gap by acquiring 3D velocity fields of a fully developed HTW in a thin liquid film using tomographic stereo particle image velocimetry (TSPIV), combined with simultaneous infrared (IR) measurements of the free-surface temperature. Experiments were conducted in a rectangular container filled with silicone oil (Prandtl number 16.1), where characteristic HTW features\u0026mdash;including roll propagation angle, roll frequency, phase velocity, and spatial wavenumber\u0026mdash;were identified. The values obtained from TSPIV measurements show quantitative agreement with those reported in previous studies. In addition, the combined TSPIV and IR measurements captured source and suction flow structures near the free surface, revealing correspondence between temperature patterns and flow organization. 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