Hydrodynamics of Towed Vertical Surface-Piercing Cylinders

Potts, Douglas; Binns, Jonathan; Marcollo, Hayden; Potts, Andrew

doi:10.1115/omae2019-95109

Cited by 3 publications

(2 citation statements)

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“…Furthermore, the forces generated on the stationary cylinder were investigated at low Re [8]. The submersed depth Z of the cylinder in terms of aspect ratio Z/D was found to have a high impact on the produced loads and wake development [9]. However, previous research findings provide the background of water cylinder interaction, this interaction needs further investigation to be predicted with a lower computational cost.…”

Section: Introductionmentioning

confidence: 98%

Wave Induced Plume and Hydrodynamic Loads Over Vertical Circular Cylinder Piercing Surface – Numerical Investigation

Shama¹,

Swidan²,

Young³

et al. 2020

Australasian Fluid Mechanics Conference (AFMC)

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Offshore platforms and other marine structures are mainly composed of a group of circular cylinders. The hydrodynamics induced wave loads and the wave profile generated on the surfacepiercing circular cylinder are a significant issue in the structure life cycle. This project aims to develop a numerical model to accurately predict the calm sea behavior around a stationary circular cylinder. The stationary cylinder was partially immersed while encountering calm waves at 10 different Froude numbers (Fr). These flat waves were based on the free stream flow velocity U from 0.5 to 5 m/s with intervals 0.5. Three main key parameters of the flow behaviour were examined as follows: visual plume structure, wave impact loads, and distribution of pressure around the cylinder. The recommended Computational Fluid Dynamics (CFD) Software, namely STAR-CCM+ was employed, utilising the new technique of Adaptive Mesh Refinement (AMR) to accurately simulate the fluid relative motion over the cylinder. The results of this numerical study were validated with previously published experimental and numerical data and show good agreement in terms of the generated bow wave height and the drag coefficient. Due to the lack of the published data on the pressure distribution over the surface piercing cylinder, part of the result discusses the pressure coefficient around the cylinder. The research outcomes are beneficial to identify the key factors of calm waves' impact on the offshore cylinders with circular shape in order to reduce the generated loads and plume structure to attain efficient design.

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Section: Introductionmentioning

confidence: 98%

Wave Induced Plume and Hydrodynamic Loads Over Vertical Circular Cylinder Piercing Surface – Numerical Investigation

Shama¹,

Swidan²,

Young³

et al. 2020

Australasian Fluid Mechanics Conference (AFMC)

View full text Add to dashboard Cite

show abstract

“…The tests were conducted up to a maximum velocity of 4 m/s for aspect ratios varying from L/D 1-40, with smooth cylinder diameters from D = 24, 48.3 and 101.6 mm. This paper presents a partial report on the drag of a towed surface-piercing cylinder from the full test program of [4].…”

Section: Introductionmentioning

confidence: 99%

Towed Vertical Surface-Piercing Cylinders

Potts¹,

Binns²,

Marcollo³

2020

Australasian Fluid Mechanics Conference (AFMC)

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Surface-piercing cylinders differ from fully submerged cylinders due to the generation of surface wakes and under increasing flow velocities the formation of a ventilated pocket in the lee of the cylinder, both of which grow with increasing velocity, with concomitant effects on the hydrodynamic loading. A series of experiments were conducted in the Towing Tank located at the Australian Maritime College (AMC). The models were attached to the towing carriage, in the standard top-down method, where the free-end tip was fully immersed in the fluid.The relative length of submergence, or immersed aspect ratio (L/D) and end conditions of the cylinder with respect to tip vortex drag effects may also impact the hydrodynamic loads and wake formation. Laboratory testing of surface-piercing cylinders to date has predominantly been confined to characterising the wakes shed from a rigid cylinder cantilevered down into the water from a towing tank carriage, which under certain test conditions will also exhibit significant Vortex-Induced-Vibration (VIV), though not adequately identified and accounted for in its magnification of drag and wake.

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Comparison of the Flow around Circular and Rectangular Emergent Cylinders with Subcritical and Supercritical Conditions

Dissanayaka

Tanaka

2023

Fluids

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There are multiple initiatives aimed at strengthening coastal communities against tsunami disaster risks, such as growing vegetation belts, construction of embankments, moats, and different hybrid alternatives. To find a solution for strengthening the coastal buildings themselves, we firstly reviewed the flow phenomena around a single emergent (circular and rectangular) cylinder (case C1), which was considered as a piloti-type column under different Froude conditions, and evaluated the formation of surface bow-waves, hydraulic jump detachment, and wall-jet-like bow-waves. Secondly, the flow characteristics were investigated under the same Froude conditions with side-by-side two-cylinder (case C2) and four-cylinder (case C4) arrays in an open channel. Surface bow-wave length (LBw) increased by 7–12% over the rectangular cylinders (RCs) compared to the circular cylinders (CCs) with a subcritical flow. For the supercritical flow with a 1/200 bed slope, hydraulic jump detachment was observed in relation to the Froude number. The observed length of the hydraulic jump detachment (Ljump) varied between 3.1–8.5% and 4.2–12.9% for the CCs and RCs in the supercritical flow with a 1/200 bed slope. In addition, the wall-jet-like bow-wave height (hjet) over the CCs was increased by 37% and 29% compared to the RCs with a supercritical flow and zero bed slope (orifice-type flow). For case C4, a hydraulic jump was observed for the supercritical flow over the horizontal channel bed. Finally, empirical equations were defined concerning the geometrical shape and arrangement based on the experiment data for the single and side-by-side configurations of the cylinders to validate the height of the wall-jet-like bow-wave as the most critical flow property.

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Hydrodynamics of Towed Vertical Surface-Piercing Cylinders

Cited by 3 publications

References 0 publications

Wave Induced Plume and Hydrodynamic Loads Over Vertical Circular Cylinder Piercing Surface – Numerical Investigation

Wave Induced Plume and Hydrodynamic Loads Over Vertical Circular Cylinder Piercing Surface – Numerical Investigation

Towed Vertical Surface-Piercing Cylinders

Comparison of the Flow around Circular and Rectangular Emergent Cylinders with Subcritical and Supercritical Conditions

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