Investigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus

Investigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus | 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 Article Investigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus Gebremeskel Kahsay Atsbha, Dinku Seyoum Zeleke, Mezid Abdella Hamza, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6843020/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 ISUZU midi bus is the primary mode of transportation for the majority of Ethiopians. Due to its blunt, rectangular appearance and high drag resistance forces, the bus has poor aerodynamic shapes and uses more fuel. Therefore, the study objective is to reduce the total aerodynamic drag force, which in turn reduces power demand, fuel consumption, and carbon dioxide emissions. As a result, the diffuser angle and bus stagnation surface shape are aerodynamically optimized. Solid Work CAD 2023 is utilized in the development of the model. Eight different car models were developed and analyzed. CFD and ANSYS Fluent 19.2 were used for the analyses. With a 15º diffuser angle in the rear weak zone and a taper in front and an arc segment on both sides in the stagnation surface, the model-6 had the lowest Cd and Fd values, measuring 0.2915 and 225.32N at 70 km/h and 0.3111 and 594.22N at 110 km/h, respectively. At 70 km/h and 110 km/h, respectively, the Cd reduction percentages attained with this model were 51.21% (48.8% due to the frontal effect and 2.41% due to the diffuser angle impact) and 50.79% (48.81% due to the frontal effect and 1.98% because of the diffuser angle impact). Compared to the baseline bus, the coefficient of drag was, on average, 51% lower. In comparison to the baseline model, model six uses 5026.6 W less power at 70 km/h and 18332.03 W less power at 110 km/h. Compared to the baseline model, the modified model six uses 1.45 L/h less gasoline at 70 km/h and 5.28 L/h less fuel at 110 km/h. At 70 km/h and 110 km/h, model six's CO2 decrease is 12.17 tons per year and 44.31 tons per year, respectively, compared to the baseline model. Physical sciences/Engineering/Mechanical engineering Physical sciences/Mathematics and computing/Computational science Aerodynamics Stagnation Drag CFD Diffuser Angle Full Text Additional Declarations No competing interests reported. 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-6843020","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":471996720,"identity":"27fc6533-aff9-499b-b008-a3ce9b423622","order_by":0,"name":"Gebremeskel Kahsay Atsbha","email":"","orcid":"","institution":"Addis Ababa Science and Technology University","correspondingAuthor":false,"prefix":"","firstName":"Gebremeskel","middleName":"Kahsay","lastName":"Atsbha","suffix":""},{"id":471996721,"identity":"fa3c40cd-e796-487c-9149-a68ee4ef4a77","order_by":1,"name":"Dinku Seyoum Zeleke","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABB0lEQVRIiWNgGAWjYDCCwwzMCM4HGIOHWC2MM2CqefBpO4CkhRmuEp8WvuO8h415GOrkDI73mG62qbGzt5dIYHzwto1Bzh6HFsnDfMnJPAyHjQ3OnDG7nXMsObFHIoHZcG4bgzEuWwwO8xgf5mE4kLjhRg5QCxtzAo9EAps0bxtDYg9+LXX1YC0W/+rtgVrYfwO11OPTAnQYc4IBSAtj22FGoMPYmIFaEnA5TBKoxXCOwWHDmWeOld3s7Tue2HPmYbPknHMShj0HcITY+TPGEm8q6uT5jjdvu/HjW7U9e3vywQ9vymzk2RtwWANxHgODAsJMRpBaCXzqIUAer5mjYBSMglEwogEAg3tTSVWrpQoAAAAASUVORK5CYII=","orcid":"","institution":"Addis Ababa Science and Technology University","correspondingAuthor":true,"prefix":"","firstName":"Dinku","middleName":"Seyoum","lastName":"Zeleke","suffix":""},{"id":471996722,"identity":"1bb2d30d-f4ed-4198-8f00-b75bd9e5a423","order_by":2,"name":"Mezid Abdella Hamza","email":"","orcid":"","institution":"Addis Ababa Science and Technology University","correspondingAuthor":false,"prefix":"","firstName":"Mezid","middleName":"Abdella","lastName":"Hamza","suffix":""},{"id":471996723,"identity":"7df3116a-6f2f-48e0-a5fc-2e7fd99ab2e1","order_by":3,"name":"Bonsa Reta Mosisa","email":"","orcid":"","institution":"Addis Ababa Science and Technology University","correspondingAuthor":false,"prefix":"","firstName":"Bonsa","middleName":"Reta","lastName":"Mosisa","suffix":""}],"badges":[],"createdAt":"2025-06-07 13:08:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6843020/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6843020/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85038724,"identity":"439bfcfb-a3e2-44e1-927d-2f13ac5a6274","added_by":"auto","created_at":"2025-06-20 08:53:52","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":803080,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscriptscientificreportfinal2ndversion.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6843020/v1_covered_b2b6f8e4-db0f-488e-abe7-2c181afd17ac.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eInvestigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Aerodynamics, Stagnation, Drag, CFD, Diffuser Angle","lastPublishedDoi":"10.21203/rs.3.rs-6843020/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6843020/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe ISUZU midi bus is the primary mode of transportation for the majority of Ethiopians. Due to its blunt, rectangular appearance and high drag resistance forces, the bus has poor aerodynamic shapes and uses more fuel. Therefore, the study objective is to reduce the total aerodynamic drag force, which in turn reduces power demand, fuel consumption, and carbon dioxide emissions. As a result, the diffuser angle and bus stagnation surface shape are aerodynamically optimized. Solid Work CAD 2023 is utilized in the development of the model. Eight different car models were developed and analyzed. CFD and ANSYS Fluent 19.2 were used for the analyses. With a 15\u0026ordm; diffuser angle in the rear weak zone and a taper in front and an arc segment on both sides in the stagnation surface, the model-6 had the lowest Cd and Fd values, measuring 0.2915 and 225.32N at 70 km/h and 0.3111 and 594.22N at 110 km/h, respectively. At 70 km/h and 110 km/h, respectively, the Cd reduction percentages attained with this model were 51.21% (48.8% due to the frontal effect and 2.41% due to the diffuser angle impact) and 50.79% (48.81% due to the frontal effect and 1.98% because of the diffuser angle impact). Compared to the baseline bus, the coefficient of drag was, on average, 51% lower. In comparison to the baseline model, model six uses 5026.6 W less power at 70 km/h and 18332.03 W less power at 110 km/h. Compared to the baseline model, the modified model six uses 1.45 L/h less gasoline at 70 km/h and 5.28 L/h less fuel at 110 km/h. At 70 km/h and 110 km/h, model six's CO2 decrease is 12.17 tons per year and 44.31 tons per year, respectively, compared to the baseline model.\u003c/p\u003e","manuscriptTitle":"Investigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-17 08:01:17","doi":"10.21203/rs.3.rs-6843020/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","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}}],"origin":"","ownerIdentity":"eb7dbd97-f22f-4f1f-b5d8-360542b0e779","owner":[],"postedDate":"June 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50165373,"name":"Physical sciences/Engineering/Mechanical engineering"},{"id":50165374,"name":"Physical sciences/Mathematics and computing/Computational science"}],"tags":[],"updatedAt":"2025-06-20T08:53:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-17 08:01:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6843020","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6843020","identity":"rs-6843020","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}