Measurement of Boundary Layer Velocity Profiles with Spatially and Temporally Varying Surface Temperature in High-Speed Flow

Measurement of Boundary Layer Velocity Profiles with Spatially and Temporally Varying Surface Temperature in High-Speed Flow | 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 Measurement of Boundary Layer Velocity Profiles with Spatially and Temporally Varying Surface Temperature in High-Speed Flow Kazuki Ozawa, Kshitij Sabnis, Paul Bruce This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9002611/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 This study presents the first time-resolved LDA measurement of streamwise streak generation induced by non-uniform surface temperature distributions in a Mach 2.75 supersonic boundary layer. To investigate the boundary layer's response to transient thermal forcing, a flat plate is constructed from alternating streamwise strips of materials with dissimilar thermal diffusivities (copper and MACOR). Preheating the model prior to wind tunnel start-up generates controlled, spanwise-periodic surface temperature gradients. To capture the rapid evolution of the flow field, a continuous-motion traverse system is employed for Laser Doppler Anemometry (LDA). This system enables the acquisition of full velocity profiles within 2 seconds, a timescale commensurate with the transient wall temperature evolution. The fidelity of this time-resolved technique is validated by the close agreement of the reconstructed velocity profiles with theoretical compound boundary-layer models (Musker and non-adiabatic wake laws). A physics-informed thermal model is used to reconstruct the wall temperature history. The measurements successfully capture the evolution of the velocity profiles and quantify the formation of coherent velocity streaks. Streak amplitudes reach approximately 5,% of the freestream value in the buffer layer and persist at 2% in the outer layer. Furthermore, the results reveal a linear relationship between the spanwise wall-temperature difference and the generated streak amplitude, establishing passive thermal forcing as a robust and predictable mechanism for flow control. Supersonic boundary layer Laser Doppler Anemometry Non-uniform surface temperature distributions Velocity streaks Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 27 Apr, 2026 Reviews received at journal 14 Apr, 2026 Reviews received at journal 08 Apr, 2026 Reviewers agreed at journal 10 Mar, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviewers invited by journal 09 Mar, 2026 Editor assigned by journal 09 Mar, 2026 Submission checks completed at journal 02 Mar, 2026 First submitted to journal 01 Mar, 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-9002611","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":604034288,"identity":"ba45d843-7b3a-453b-a77a-cffe92a256bb","order_by":0,"name":"Kazuki Ozawa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIiWNgGAWjYBACCSgtx8be2ABi8DCwQ0QMCGkx5uM5CNXCTKSWxHkSCVAmIS2SDcyHP/xss2Nsk3zcurmg4p4MfzMD44cfDIeNcWmRZmBLMOxtS2Zmk05suz3jTDGPxGEGZskehsNmuLTIMfAYJPBuY2YDa+FtS+BhOAwyiOGwDT4tB/9uq+dhkzwI1PIvgUceaMtvfFqkGXgMm3m3HZZgk2AEamlI4DE4zMAGsgWnwySb2ZKZZf8dN2DjAfnlWAKP4WHGNsseg3Sc3pc43nz445sz1fXz248/u11Qk2AvBxS58aPC2rABlx5mTDZjA55YwaN9FIyCUTAKRgEcAADnTUvGulLtXwAAAABJRU5ErkJggg==","orcid":"","institution":"Imperial College London","correspondingAuthor":true,"prefix":"","firstName":"Kazuki","middleName":"","lastName":"Ozawa","suffix":""},{"id":604034289,"identity":"8e37cc97-5280-45fa-9255-9235c3630e49","order_by":1,"name":"Kshitij Sabnis","email":"","orcid":"","institution":"Queen Mary University of London","correspondingAuthor":false,"prefix":"","firstName":"Kshitij","middleName":"","lastName":"Sabnis","suffix":""},{"id":604034290,"identity":"8339bfb1-c994-4255-aa85-cbb5e8e10b7f","order_by":2,"name":"Paul Bruce","email":"","orcid":"","institution":"Imperial College London","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Bruce","suffix":""}],"badges":[],"createdAt":"2026-03-01 15:53:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9002611/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9002611/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104781463,"identity":"64298aee-6712-4069-932b-08e51b41059d","added_by":"auto","created_at":"2026-03-17 07:55:44","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9119195,"visible":true,"origin":"","legend":"","description":"","filename":"ExiFTimeresolvedLDAspringernature.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9002611/v1_covered_a6ab1033-ae2a-48cf-ad49-8af4961a0a05.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Measurement of Boundary Layer Velocity Profiles with Spatially and Temporally Varying Surface Temperature in High-Speed Flow","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":"Supersonic boundary layer, Laser Doppler Anemometry, Non-uniform surface temperature distributions, Velocity streaks","lastPublishedDoi":"10.21203/rs.3.rs-9002611/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9002611/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"This study presents the first time-resolved LDA measurement of streamwise streak generation induced by non-uniform surface temperature distributions in a Mach 2.75 supersonic boundary layer. To investigate the boundary layer's response to transient thermal forcing, a flat plate is constructed from alternating streamwise strips of materials with dissimilar thermal diffusivities (copper and MACOR). Preheating the model prior to wind tunnel start-up generates controlled, spanwise-periodic surface temperature gradients. To capture the rapid evolution of the flow field, a continuous-motion traverse system is employed for Laser Doppler Anemometry (LDA). This system enables the acquisition of full velocity profiles within 2 seconds, a timescale commensurate with the transient wall temperature evolution. The fidelity of this time-resolved technique is validated by the close agreement of the reconstructed velocity profiles with theoretical compound boundary-layer models (Musker and non-adiabatic wake laws). A physics-informed thermal model is used to reconstruct the wall temperature history. 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