Systematic Evaluation of One-Dimensional Unsteady Friction Models in Simple Pipelines |
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Authors: | John P. Vítkovsky Anton Bergant Angus R. Simpson Martin F. Lambert |
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Affiliation: | 1Graduate Hydrologist, Dept. of Natural Resources and Mines, Water Assessment Group, Indooroopilly QLD 4068, Australia. E-mail: john.vitkovsky@nrm.gov.qld.au 2Head, Research, Instrumentation and Control Engineering Dept., Litostroj E.I. d.o.o., 1000 Ljubljana, Slovenia. E-mail: anton.bergant@litostroj-ei.si 3Head Professor, Centre for Applied Modelling in Water Engineering, School of Civil and Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia. E-mail: asimpson@civeng.adelaide.edu.au 4Associate Professor, Centre for Applied Modelling in Water Engineering, School of Civil and Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia (corresponding author). E-mail: mlambert@civeng.adelaide.edu.au
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Abstract: | In this paper, basic unsteady flow types and transient event types are categorized, and then unsteady friction models are tested for each type of transient event. One important feature of any unsteady friction model is its ability to correctly model frictional dissipation in unsteady flow conditions under a wide a range of possible transient event types. This is of importance to the simulation of transients in pipe networks or pipelines with various devices in which a complex series of unsteady flow types are common. Two common one-dimensional unsteady friction models are considered, namely, the constant coefficient instantaneous acceleration-based model and the convolution-based model. The modified instantaneous acceleration-based model, although an improvement, is shown to fail for certain transient event types. Additionally, numerical errors arising from the approximate implementation of the instantaneous acceleration-based model are determined, suggesting some previous good fits with experimental data are due to numerical error rather than the unsteady friction model. The convolution-based model is successful for all transient event types. Both approaches are tested against experimental data from a laboratory pipeline. |
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Keywords: | Friction Pipelines Unsteady flow Numerical analysis Errors Transients One-dimensional models |
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