Experimental and numerical study of primary instability of a two-phase stratified flow in a circular pipe

Experimental and numerical study of primary instability of a two-phase stratified flow in a circular pipe | 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 Experimental and numerical study of primary instability of a two-phase stratified flow in a circular pipe Yakov Nezihovski, Ilya Barmak, Alexander Gelfgat, Gerrit Maik Horstmann, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4706348/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The onset of the primary instability of two-phase air-water stratified flow in a circular pipe was studied experimentally by two independent non-intrusive techniques. The techniques analyze the steady or oscillatory response of either a laser beam passing through the air-water interface, or of an echo of an ultrasound wave reflected from the interface. The experiments are accompanied by linear stability analysis performed in both Cartesian and bipolar coordinates, thus yielding two independently obtained numerical results for comparison. The critical values of the phases’ superficial velocities corresponding to the flow primary instability calculated numerically by the two independent methods agree well with each other. The computed stability diagram shows that instability sets in owing to long-wave disturbances at large holdups, while at smaller holdups, the most unstable perturbations appear as finite-length (short) waves. A comparison of the experimental and numerical results shows a good agreement for the long-wave instability. For the short-wave instability, the measured critical superficial velocities are below the computed ones, while the frequencies found experimentally for supercritical oscillatory flow states agree with the numerical predictions. Several additional peaks in the frequency spectra are observed in the experiments. By comparing these frequencies with the numerical spectra, we argue that they correspond to stable eigenmodes with close to zero decay rates, which can be triggered either by non-linear mechanisms, or become unstable because of experimental imperfections. Two-phase stratified flow non-intrusive measurement ultrasound Doppler velocimetry interfacial waves stability boundary critical disturbance. Full Text Additional Declarations No competing interests reported. Supplementary Files TableS1.docx Cite Share Download PDF Status: Posted Version 1 posted 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4706348","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":331756681,"identity":"7fa5b5de-732f-45f4-99a6-7ef918a2208b","order_by":0,"name":"Yakov Nezihovski","email":"","orcid":"","institution":"Tel-Aviv University","correspondingAuthor":false,"prefix":"","firstName":"Yakov","middleName":"","lastName":"Nezihovski","suffix":""},{"id":331756682,"identity":"1e578c5c-a65f-4f53-87fd-67545f791593","order_by":1,"name":"Ilya Barmak","email":"","orcid":"","institution":"Soreq NRC","correspondingAuthor":false,"prefix":"","firstName":"Ilya","middleName":"","lastName":"Barmak","suffix":""},{"id":331756683,"identity":"ca7d4c77-dcd4-476c-a4e5-3db80f120171","order_by":2,"name":"Alexander Gelfgat","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAz0lEQVRIiWNgGAWjYFAC5oYPQFIOxuXhI6yFsXEGA4OBMQ9MCxuxWhJ7YHyCWuTdGxsbv9T8Sd/PfsaA4UcNgwxBLYZnDjY2yxwzyO3hyTFg7DlGhMMMZyS2P5ZgA2phyDFg4G0gRsv8h43NEv8M0nn43xgw/iVGi7wEY2PjxzaDBB6JHANmomwx4ElsbGbsMzbsufGs4LDMMQkibGk/fLDxxzc5efb+5I0P39TY2PMTtOUAMP5h0QhkSxDSALSlARiZPwirGwWjYBSMgpEMANAhOTM8I0dVAAAAAElFTkSuQmCC","orcid":"","institution":"Tel-Aviv University","correspondingAuthor":true,"prefix":"","firstName":"Alexander","middleName":"","lastName":"Gelfgat","suffix":""},{"id":331756684,"identity":"22bbe627-dfa9-4092-a161-d844de14401e","order_by":3,"name":"Gerrit Maik Horstmann","email":"","orcid":"","institution":"Helmholtz-Zentrum Dresden-Rossendorf","correspondingAuthor":false,"prefix":"","firstName":"Gerrit","middleName":"Maik","lastName":"Horstmann","suffix":""},{"id":331756685,"identity":"4853a276-a8de-4650-aefd-87eb9bee2e45","order_by":4,"name":"Amos Ullmann","email":"","orcid":"","institution":"Tel-Aviv University","correspondingAuthor":false,"prefix":"","firstName":"Amos","middleName":"","lastName":"Ullmann","suffix":""},{"id":331756686,"identity":"0386d183-b75d-4a31-ba70-7786f9e08c21","order_by":5,"name":"Neima Brauner","email":"","orcid":"","institution":"Tel-Aviv University","correspondingAuthor":false,"prefix":"","firstName":"Neima","middleName":"","lastName":"Brauner","suffix":""}],"badges":[],"createdAt":"2024-07-08 14:38:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4706348/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4706348/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":61132025,"identity":"71a4f69a-c660-45da-b234-ebd9fbfd02cd","added_by":"auto","created_at":"2024-07-26 04:28:25","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1285280,"visible":true,"origin":"","legend":"","description":"","filename":"PapercircularpipeexperimentEF1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4706348/v1_covered_377524de-cf95-4adf-8b56-b45ea4c7c96d.pdf"},{"id":61131541,"identity":"f9e50403-02c9-423a-b0f5-0449397e491a","added_by":"auto","created_at":"2024-07-26 04:20:08","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":31191,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-4706348/v1/8de353916ed48bdb9f63680e.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Experimental and numerical study of primary instability of a two-phase stratified flow in a circular pipe","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Two-phase stratified flow, non-intrusive measurement, ultrasound Doppler velocimetry, interfacial waves, stability boundary, critical disturbance. 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