This paper describes an experiment that was carried out in the Twisted Flow Wind Tunnel at The University of Auckland to measure a detailed set of pressure distributions on a rigid 1/15th scale model of a modern asymmetric spinnaker. It was observed that the pressures varied considerably up the height of the spinnaker. The fine resolution of pressure taps allowed the extent of leading edge separation bubble, pressure recovery region, and effect of sail curvature to be observed quite clearly. It was found that the shape of the pressure distributions could be understood in terms of conventional aerodynamic theory. The sail performed best at an apparent wind angle of about 55°, which is its design angle, and the effect of heel was more pronounced near the head than the foot. Analysis of pressure time histories allows the large scale vortex shedding to be detected in the separation region, with a Strouhal number in the range 0.1–0.3, based on local sail chord length.

Wind-tunnel pressure measurements on model-scale rigid downwind sails

In this paper, we conducted a selective review on the recent progress in physics insight and modeling of flexible cylinder flow-induced vibrations (FIVs). FIVs of circular cylinders include vortex-induced vibrations (VIVs) and wake-induced vibrations (WIVs), and they have been the center of the fluid-structure interaction (FSI) research in the past several decades due to the rich physics and the engineering significance. First, we summarized the new understanding of the structural response, hydrodynamics, and the impact of key structural properties for both the isolated and multiple circular cylinders. The complex FSI phenomena observed in experiments and numerical simulations are explained carefully via the analysis of the vortical wake topology. Following up with several critical future questions to address, we discussed the advancement of the artificial intelligent and machine learning (AI/ML) techniques in improving both the understanding and modeling of flexible cylinder FIVs. Though in the early stages, several AL/ML techniques have shown success, including auto-identification of key VIV features, physics-informed neural network in solving inverse problems, Gaussian process regression for automatic and adaptive VIV experiments, and multi-fidelity modeling in improving the prediction accuracy and quantifying the prediction uncertainties. These preliminary yet promising results have demonstrated both the opportunities and challenges for understanding and modeling of flexible cylinder FIVs in today ’ s big data era. to simulate this nonlinear FSI problem. 5 High-fidelity CFD tools have shown great

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Flexible cylinder flow-induced vibration

Flow-induced vibration control of a circular cylinder by using flexible and rigid splitter plates

Novel geometries of serrated helical strakes to suppress vortex-induced vibrations and reduce drag

Transmission towers with steel tubes or so-called tubular towers are widely used for ultra-high voltage (UHV) transmission because of their overall higher strength and stability, and better wind re...

Vortex-Induced Vibration and Countermeasure of a Tubular Transmission Tower

Experimental investigation on the VIV of two side-by-side risers fitted with triple helical strakes under coupled interference effect

The dynamic evolution of fluid strouhal number under flow fields around flexible vertical pipe groups

We present experiment and analysis of the effectiveness of a flexible splitter plate in the suppression of vortex-induced vibration (VIV) of a circular cylinder. The important finding is that it is not necessary to suppress VIV by a full-span flexible splitter plate, while efficient control can be achieved by a finite-span one. The fluid-structure interaction and control mechanism are revealed by analysis of wake evolution and force characteristics. 

Suppression of vortex-induced vibration of a circular cylinder by a finite-span flexible splitter plate

Combined effect of bending stiffness and streamwise length of the attached flexible splitter plate on the vortex-induced vibration of a circular cylinder

Liping Feng

Papers

Flow-induced vibration control of a circular cylinder by using flexible and rigid splitter plates

Experimental investigation on the VIV of two side-by-side risers fitted with triple helical strakes under coupled interference effect

The dynamic evolution of fluid strouhal number under flow fields around flexible vertical pipe groups

Suppression of vortex-induced vibration of a circular cylinder by a finite-span flexible splitter plate

Combined effect of bending stiffness and streamwise length of the attached flexible splitter plate on the vortex-induced vibration of a circular cylinder