Three-Dimensional Flow Structures in Bend-Straightened Sections within Continuous Bend Channels

Three-Dimensional Flow Structures in Bend-Straightened Sections within Continuous Bend Channels | 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 Three-Dimensional Flow Structures in Bend-Straightened Sections within Continuous Bend Channels liang zhong, xinming yan, jian pan, xin guan, xiangyu xu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7306410/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Apr, 2026 Read the published version in Environmental Fluid Mechanics → Version 1 posted 11 You are reading this latest preprint version Abstract To clarify the complex hydrodynamics of bend-straightened reaches inside continuous meandering rivers, three dimensional simulations were performed with a Reynolds Stress Model (RSM) coupled to the Volume of Fluid (VOF) method. The numerical experiments examined water surface fluctuations, velocity structures, and turbulent kinetic energy (TKE) distributions under different channel curvature ratios K and Froude numbers Fr . Channel stability, ecological value, and navigation management strategies were also evaluated. The results show that bifurcation and confluence nodes are hydraulically intricate sections of the straightened reach. They display marked water surface fluctuations, strong secondary flows, and clear shear layers that create separation zones, recirculation cells, flow deflection regions, and core flow corridors. Water surface change, separation zone size, and secondary flow strength respond almost linearly to Fr , but they respond nonlinearly to K . Successive straightened units interact with one another; an upstream shift of the velocity core and its secondary circulation can persist downstream, lowering the flow share through bends, enlarging downstream separation zone, weakening secondary flows, and amplifying water surface fluctuations. From a functional viewpoint, rectilinear reaches carry higher and more uniform velocities. This favors navigation but increases the risk of bed scouring. Bends, on the other hand, have lower velocities and more complex flow structures. Their separation and slack water zones encourage sediment deposition and create refuges that benefit aquatic habitats. Therefore, sequences of bend straightening units can help balance navigation efficiency with ecological enhancement in river management. continuous bend bend-straightened confluence separation zone secondary flow turbulent kinetic energy Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Apr, 2026 Read the published version in Environmental Fluid Mechanics → Version 1 posted Editorial decision: Revision requested 23 Jan, 2026 Reviews received at journal 23 Jan, 2026 Reviewers agreed at journal 10 Dec, 2025 Reviews received at journal 10 Dec, 2025 Reviewers agreed at journal 09 Dec, 2025 Reviewers agreed at journal 08 Dec, 2025 Reviewers agreed at journal 27 Nov, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 29 Aug, 2025 Submission checks completed at journal 11 Aug, 2025 First submitted to journal 06 Aug, 2025 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. 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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-7306410","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":525804940,"identity":"1f0e3cd1-96bd-47c3-89ad-c6ac6ecff467","order_by":0,"name":"liang 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The numerical experiments examined water surface fluctuations, velocity structures, and turbulent kinetic energy (TKE) distributions under different channel curvature ratios \u003cem\u003eK\u003c/em\u003e and Froude numbers \u003cem\u003eFr\u003c/em\u003e. Channel stability, ecological value, and navigation management strategies were also evaluated. The results show that bifurcation and confluence nodes are hydraulically intricate sections of the straightened reach. They display marked water surface fluctuations, strong secondary flows, and clear shear layers that create separation zones, recirculation cells, flow deflection regions, and core flow corridors. Water surface change, separation zone size, and secondary flow strength respond almost linearly to \u003cem\u003eFr\u003c/em\u003e, but they respond nonlinearly to \u003cem\u003eK\u003c/em\u003e. Successive straightened units interact with one another; an upstream shift of the velocity core and its secondary circulation can persist downstream, lowering the flow share through bends, enlarging downstream separation zone, weakening secondary flows, and amplifying water surface fluctuations. From a functional viewpoint, rectilinear reaches carry higher and more uniform velocities. This favors navigation but increases the risk of bed scouring. Bends, on the other hand, have lower velocities and more complex flow structures. Their separation and slack water zones encourage sediment deposition and create refuges that benefit aquatic habitats. Therefore, sequences of bend straightening units can help balance navigation efficiency with ecological enhancement in river management.\u003c/p\u003e","manuscriptTitle":"Three-Dimensional Flow Structures in Bend-Straightened Sections within Continuous Bend Channels","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-11 00:16:26","doi":"10.21203/rs.3.rs-7306410/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-23T17:22:01+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-23T11:12:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"218313853988968002257001232909102753814","date":"2025-12-10T15:23:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-10T14:47:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"72410787543833893552940236950631492300","date":"2025-12-09T22:21:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"308018865274244531985253690605799979439","date":"2025-12-08T16:51:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"255573158117604276385779157932084424783","date":"2025-11-28T03:00:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-29T19:05:35+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-29T19:47:08+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-11T15:26:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Fluid Mechanics","date":"2025-08-06T06:31:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-fluid-mechanics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"efmc","sideBox":"Learn more about [Environmental Fluid Mechanics](http://link.springer.com/journal/10652)","snPcode":"10652","submissionUrl":"https://submission.nature.com/new-submission/10652/3","title":"Environmental Fluid Mechanics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2875a574-c781-41bc-9a5f-29529bd5968f","owner":[],"postedDate":"October 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T15:59:49+00:00","versionOfRecord":{"articleIdentity":"rs-7306410","link":"https://doi.org/10.1007/s10652-026-10092-2","journal":{"identity":"environmental-fluid-mechanics","isVorOnly":false,"title":"Environmental Fluid Mechanics"},"publishedOn":"2026-04-30 15:57:33","publishedOnDateReadable":"April 30th, 2026"},"versionCreatedAt":"2025-10-11 00:16:26","video":"","vorDoi":"10.1007/s10652-026-10092-2","vorDoiUrl":"https://doi.org/10.1007/s10652-026-10092-2","workflowStages":[]},"version":"v1","identity":"rs-7306410","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7306410","identity":"rs-7306410","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}