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oai:recercat.cat:2117/3324642026-02-07T01:10:02Zcom_2072_1033col_2072_452949

Analysis of the unsteady wake of a full bottomed ship in shallow water Shevchuk, Ivan Kornev, Nikolai Àrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits Finite element method Marine engineering Hybrid RANS/LES, shallow water, unsteady wake, vibration The paper is devoted to the analysis of the unsteady hydrodynamic processes taking place in the ship wake under shallow water conditions. The motivation of the research is the determination of the reasons for the rise of strong vibration in the stern of inland cruise ships in the waterways with considerable depth restriction. As a research tool the hybrid URANS/LES approach of Kornev et al. [1] is selected in order to capture the influence of nonstationary vortical structures on the velocity oscillations in the propeller plane. As it will be shown, URANS method cannot reproduce these flow features. The flow is studied in a single-phase and in a two-phase formulation. Influence of the free surface, depth Froude number and depth to draft ratio on the wake is analyzed. The adverse pressure gradient in the stern region causes massive separations of the boundary layer. On account of the separations the velocity oscillations in the wake are turned out to be strongly dependent on the under keel clearance. On the other hand, it is shown, that at high F rH the wave pattern can significantly influence the viscous wake and cause the suppression of the velocity oscillations due to the decrease of the water level. Possible effect of the wake unsteadiness on the propeller performance in such circumstances is discussed. 2015 Conference report Shevchuk, I.; Kornev, N. Analysis of the unsteady wake of a full bottomed ship in shallow water. A: MARINE VI. "MARINE VI : proceedings of the VI International Conference on Computational Methods in Marine Engineering". CIMNE, 2015, p. 627-638. ISBN 978-84-943928-6-3. 978-84-943928-6-3 https://hdl.handle.net/2117/332464 eng Open Access 12 p. application/pdf CIMNE