Wake dynamics of a square cylinder while moving upward in quiescent water

[en] We experimentally investigate the wake dynamics of a square cylinder rising through quiescent water over a range of Froude numbers (Fr). Time-resolved particle image velocimetry provides velocity and vorticity fields that enable pressure reconstruction and vortex characterization. Diagnostics based on swirl strength (λci), the Okubo–Weiss parameter (W), and a shear–vortex interaction measure (Λ) reveal that the wake is governed by a persistent pair of counter-rotating vortices rather than by periodic shedding. Circulation exhibits a two-regime dependence on Fr, with a sharp increase below Fr≈1 and saturation above this threshold, mirroring entrainment force scaling reported previously. While vortex area remains nearly constant, swirl strength and negative-W regions expand with Fr, indicating that entrainment enhancement arises from intensified rotation rather than an enlarged vortex footprint. These findings provide new physical insight into vortex-free-surface interactions and enrich the understanding of entrainment mechanisms in unsteady wakes, with implications for multiphase flows and the hydrodynamic design of naval and offshore structures.

Disciplines :

Physics

Author, co-author :

Ashraf, Intesaaf ; Université de Liège - ULiège > Département de physique > Physique statistique

Tiwari, Neetu ; Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad 2 , Sangareddy, 502285 Telangana,

Dorbolo, Stéphane ; Université de Liège - ULiège > Complex and Entangled Systems from Atoms to Materials (CESAM)

Language :

English

Title :

Wake dynamics of a square cylinder while moving upward in quiescent water

Publication date :

01 December 2025

Journal title :

Physics of Fluids

ISSN :

1070-6631

eISSN :

1089-7666

Publisher :

AIP Publishing

Volume :

Issue :

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

https://pubs.aip.org/aip/pof/article-pdf/doi/10.1063/5.0297356/20841941/122132_1_5.0297356.pdf

Funders :

FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture
ULiège - University of Liège

Available on ORBi :

since 22 December 2025

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