Numerical Simulation of Cross-Flow Vortex-Induced Vibration of Hexagonal Cylinders with Face and Corner Orientations at Low Reynolds Number

Abstract

Vortex-induced vibrations (VIV) of hexagonal cylinders at Reynolds number of 1000 and mass ratio of 2 are studied numerically. In the numerical model, the Navier–Stokes equations are solved using finite volume method, and the fluid-structure interaction (FSI) is modelled using Arbitrary Lagrangian Eulerian (ALE) Scheme. The numerical model accounts for the cross-flow vibration of the cylinders, and is validated against published experimental and numerical results. In order to account for different angles of attack, the hexagonal cylinders are studied in the corner and face orientations. The results are compared with the published results of circular and square cylinders. Current results show that within the studied range of reduced velocities (up to 20), unlike circular and square cylinders, no lock-in response is observed in the hexagonal cylinders. The maximum normalized VIV amplitudes of the hexagonal cylinders are 0.45, and are significantly lower than those of circular and square cylinders. Vortex shedding regimes of the corner-oriented hexagons are mostly irregular. However, in the face-oriented hexagons, the shedding modes are more similar to the typical P + S and 2P modes.

Soil Structure Interaction Effects on Stability of HP/HT Unburied Subsea Pipelines Using a Probabilistic-Based Approach

“…Recently Mina et al (2020) developed fragility curves that account for the interaction between buckling and earthquakes and Triantafyllaki et al (2020) performed 3D numerical simulations of a partially embedded (unburied) pipeline in to assess its vulnerability to a fault rupture. Other authors (such as Karampour et al (2018Karampour et al ( , 2015, Alrzai and , Binazir et al (2019), Stephan et al (2016) and Piran at al. (2020) investigated the stability of subsea pipelines and pipe-in-pipe systems under hydrostatic, hydrodynamic, thermal and combined actions.…”

Safe Design of Subsea Pipelines to Combined Seismic and Thermal Loading

“…In such environments, thicker pipelines with the OD/t ratio as low as 10 are required due to the substantial hydrostatic pressure [3][4][5][6]. Moreover, the pipeline may need to be installed on seabed with escarpments that increases the risk of thermal buckling [7][8][9], free-spanning [10] and vortex-induced vibrations [11]. The interaction between thermal loading and local collapse poses strict design conditions for this type of infrastructures, and has been studied experimentally [7,8] and numerically [12] in rigid pipelines and pipe-inpipe systems [13,14].…”

Numerical Investigation of Vortex Shedding from a 5:1 Rectangular Cylinder at Different Angles of Attack

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