Numerical investigation of KC number effect on wave-induced scour around pile groups

Numerical investigation of KC number effect on wave-induced scour around pile groups | 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 Numerical investigation of KC number effect on wave-induced scour around pile groups mengmeng Gong, Xiaochao Li, Xi Zhou This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9290651/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Wave-induced local scour poses a significant threat to the stability of pile groups widely used in coastal and offshore engineering. Existing studies mainly focus on twin-pile configurations under low KC numbers, while the scour mechanism of complex multi-pile systems under high KC numbers remains unclear. In this study, a three-dimensional numerical model based on REEF3D is established, which solves the RANS equations with k - ω turbulence closure and tracks the free surface using the level set method. After model validation, the model is applied to investigate the local scour characteristics of three pile groups (2×1, 2×2, 2×4) with a fixed gap ratio of 1.8, covering a KC number range of 6.24 to 63.96. The results show that the local scour around pile groups is dominated by gap flow and wake vortices rather than horseshoe vortices. The maximum scour always occurs at the first-row piles. The scour mechanism transits at a critical KC number of 46.2: gap jet dominates when KC < 46.2, while wake vortex becomes dominant when KC ≥ 46.2. Increasing the number of pile rows can reduce the maximum scour depth, but the mitigation effect decreases gradually with more rows. This study reveals the wave-induced scour mechanism of multi-pile groups under a wide KC range, fills the research gap under high KC numbers, and provides a theoretical basis for the anti-scour design of coastal bridge pile foundations. pile group local scour flow structures KC number REEF3D Full Text Additional Declarations No competing interests reported. Supplementary Files rawdataofthetimehistorycurve.zip Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 15 May, 2026 Reviews received at journal 15 May, 2026 Reviews received at journal 29 Apr, 2026 Reviewers agreed at journal 25 Apr, 2026 Reviewers agreed at journal 23 Apr, 2026 Reviewers agreed at journal 23 Apr, 2026 Reviewers invited by journal 23 Apr, 2026 Editor assigned by journal 23 Apr, 2026 Editor invited by journal 23 Apr, 2026 Submission checks completed at journal 19 Apr, 2026 First submitted to journal 19 Apr, 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. 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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-9290651","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":632155852,"identity":"32137130-89d2-4ba1-8b7b-94153ee23809","order_by":0,"name":"mengmeng Gong","email":"","orcid":"","institution":"Changsha University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"mengmeng","middleName":"","lastName":"Gong","suffix":""},{"id":632155854,"identity":"59207b34-4983-421e-8f08-28d7fddaa54f","order_by":1,"name":"Xiaochao Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvUlEQVRIiWNgGAWjYBACPmYg8QHG4yFGCxtQC+MMMItoLUDMzEOaFnYew882NXWJ8+c3MD5428Ygb07YYWzJ0jnHDiduOMbAbDi3jcFwZwNBLczHmHMbDiRuYGNgk+ZtY0gwOEBQC2Mbs2UD0GFtDOy/idQCtIWxgTmx4RiQTaQWtmTJnmOHjTccS2yWnHNOwnADIS38/GcMP/yoqZOd33z44Ic3ZTbyBG1BAowNQEKCePWjYBSMglEwCnADAEkjNFzOfRsFAAAAAElFTkSuQmCC","orcid":"","institution":"Changsha University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Xiaochao","middleName":"","lastName":"Li","suffix":""},{"id":632155856,"identity":"5c89da7d-0541-41cf-ba21-2d4fa5bb6643","order_by":2,"name":"Xi Zhou","email":"","orcid":"","institution":"Changsha University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xi","middleName":"","lastName":"Zhou","suffix":""}],"badges":[],"createdAt":"2026-04-01 10:49:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9290651/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9290651/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108803751,"identity":"8aa3adb9-28a4-4153-8394-0c9ddbe64206","added_by":"auto","created_at":"2026-05-08 15:05:41","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1531345,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9290651/v1_covered_42480a53-18a5-4bcf-8e12-3596c934ca96.pdf"},{"id":108452603,"identity":"dba42dbf-29e1-42c1-aa77-0d86af3c4a1e","added_by":"auto","created_at":"2026-05-04 20:04:55","extension":"zip","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2528360,"visible":true,"origin":"","legend":"","description":"","filename":"rawdataofthetimehistorycurve.zip","url":"https://assets-eu.researchsquare.com/files/rs-9290651/v1/7ddfd6745d610622d64a9074.zip"}],"financialInterests":"No competing interests reported.","formattedTitle":"Numerical investigation of KC number effect on wave-induced scour around pile groups","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"pile group, local scour, flow structures, KC number, REEF3D","lastPublishedDoi":"10.21203/rs.3.rs-9290651/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9290651/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWave-induced local scour poses a significant threat to the stability of pile groups widely used in coastal and offshore engineering. Existing studies mainly focus on twin-pile configurations under low \u003cem\u003eKC\u003c/em\u003e numbers, while the scour mechanism of complex multi-pile systems under high \u003cem\u003eKC\u003c/em\u003e numbers remains unclear. In this study, a three-dimensional numerical model based on REEF3D is established, which solves the RANS equations with \u003cem\u003ek\u003c/em\u003e-\u003cem\u003eω\u003c/em\u003e turbulence closure and tracks the free surface using the level set method. After model validation, the model is applied to investigate the local scour characteristics of three pile groups (2\u0026times;1, 2\u0026times;2, 2\u0026times;4) with a fixed gap ratio of 1.8, covering a \u003cem\u003eKC\u003c/em\u003e number range of 6.24 to 63.96. The results show that the local scour around pile groups is dominated by gap flow and wake vortices rather than horseshoe vortices. The maximum scour always occurs at the first-row piles. The scour mechanism transits at a critical \u003cem\u003eKC\u003c/em\u003e number of 46.2: gap jet dominates when \u003cem\u003eKC\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;46.2, while wake vortex becomes dominant when \u003cem\u003eKC\u003c/em\u003e\u0026thinsp;\u0026ge;\u0026thinsp;46.2. Increasing the number of pile rows can reduce the maximum scour depth, but the mitigation effect decreases gradually with more rows. This study reveals the wave-induced scour mechanism of multi-pile groups under a wide \u003cem\u003eKC\u003c/em\u003e range, fills the research gap under high \u003cem\u003eKC\u003c/em\u003e numbers, and provides a theoretical basis for the anti-scour design of coastal bridge pile foundations.\u003c/p\u003e","manuscriptTitle":"Numerical investigation of KC number effect on wave-induced scour around pile groups","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-04 20:04:51","doi":"10.21203/rs.3.rs-9290651/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-15T09:56:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T04:17:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-29T09:38:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"291017293574566176720412698772238292927","date":"2026-04-26T01:22:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"332826423416525602563461704519161558210","date":"2026-04-24T03:11:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"72114572012146618005974437286182855937","date":"2026-04-24T03:01:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-24T00:33:35+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-23T23:46:52+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-23T11:54:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-19T09:41:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Applied Sciences","date":"2026-04-19T09:33:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"786e9761-a3e5-4f6a-b35d-2b20355d883e","owner":[],"postedDate":"May 4th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-15T09:56:04+00:00","index":34,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T04:17:27+00:00","index":33,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-29T09:38:10+00:00","index":32,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T20:04:51+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-04 20:04:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9290651","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9290651","identity":"rs-9290651","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}