{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T16:40:27Z","timestamp":1770741627509,"version":"3.49.0"},"reference-count":31,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,5,21]],"date-time":"2025-05-21T00:00:00Z","timestamp":1747785600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Water"],"abstract":"<jats:p>This study presents an elastic one-dimensional numerical model to simulate the filling process of a large-scale, partially drained pipeline with an undulating profile, incorporating bypass systems. The model uses the Method of Characteristics to solve water hammer equations and integrates the Discrete Gas Cavity Model to capture column separation effects. Validation is performed using two experimental test rigs and comparisons with existing numerical models, showing RMSE values between 1.06 and 7.95. The results highlight three key findings: (1) oversized bypasses generate severe transient pressures; (2) effective air management enables higher filling flow rates, significantly reducing filling time; and (3) bypass lines help dampen pressure fluctuations, with a notable drop in \u2206H from 528 m to 6.8 m occurring in stage b, following the release of trapped air. Additionally, this study challenges the practicality of the AWWA\u2019s recommended pipeline filling velocity limit of 0.3 m\/s, showing that strict adherence to this guideline is often unrealistic for large-scale systems. Overall, the findings emphasize the need for a balanced design approach that reduces transient risks while maintaining operational efficiency in large-scale pipelines.<\/jats:p>","DOI":"10.3390\/w17101544","type":"journal-article","created":{"date-parts":[[2025,5,21]],"date-time":"2025-05-21T06:31:27Z","timestamp":1747809087000},"page":"1544","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Numerical Investigation into the Performance of Bypass Systems During Filling and Air Removal in Partially Drained Pipelines"],"prefix":"10.3390","volume":"17","author":[{"given":"Samane","family":"Aghaei","sequence":"first","affiliation":[{"name":"Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol 4714871167, Iran"}]},{"given":"Mehdi","family":"Hamidi","sequence":"additional","affiliation":[{"name":"Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol 4714871167, Iran"}]},{"given":"Ahmad","family":"Malekpour","sequence":"additional","affiliation":[{"name":"WSP Canada Inc., 150 Commerce Valley Dr. W, Thornhill, ON L3T 7Z3, Canada"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5222-0679","authenticated-orcid":false,"given":"Mohsen","family":"Besharat","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1061\/(ASCE)0733-9429(2002)128:6(635)","article-title":"Observations of Air\u2013Water Interaction in a Rapidly Filling Horizontal Pipe","volume":"128","author":"Zhou","year":"2002","journal-title":"J. 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