2020-03-262020-03-262019Journal of Hydraulic Research00221686https://hdl.handle.net/20.500.12585/9194The occurrence of sub-atmospheric pressure in the drainage of pipelines containing an air pocket has been known as a major cause of several serious problems. Accordingly, some system malfunction and pipe buckling events have been reported in the literature. This case has been studied experimentally and numerically in the current research considering objectives for a better understanding of: (i) the emptying process, (ii) the main parameters influencing the drainage, and (iii) the air-water interface deformation. Also, this research demonstrates the ability of a computational fluid dynamic (CFD) model in the simulation of this event. The effects of the air pocket size, the percentage and the time of valve opening on the pressure variation have been studied. Results show the pipeline drainage mostly occurs due to backflow air intrusion. The worst case scenario is associated with a fast valve opening when a tiny air pocket exists in the pipeline. © 2019, © 2019 International Association for Hydro-Environment Engineering and Research.Recurso electrónicoapplication/pdfenghttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/article10.1080/00221686.2019.1625819Computational fluid dynamics (CFD)Emptying processEntrapped air simulationExperimental set-upRealizable k-ϵ turbulence modelSub-atmospheric pressureVolume of fluid (VOF) multiphase modelAirAtmospheric pressurePhase interfacesPipelinesTurbulence modelsAir water interfacesEntrapped airsExperimental set upMain parametersMultiphase modelPressure variationsSubatmospheric pressuresWorst case scenarioComputational fluid dynamicsinfo:eu-repo/semantics/restrictedAccessAtribución-NoComercial 4.0 InternacionalUniversidad Tecnológica de BolívarRepositorio UTB5720542020257193337460560742827005719311302335568240000