Picture of model of urban architecture

Open Access research that is exploring the innovative potential of sustainable design solutions in architecture and urban planning...

Strathprints makes available scholarly Open Access content by researchers in the Department of Architecture based within the Faculty of Engineering.

Research activity at Architecture explores a wide variety of significant research areas within architecture and the built environment. Among these is the better exploitation of innovative construction technologies and ICT to optimise 'total building performance', as well as reduce waste and environmental impact. Sustainable architectural and urban design is an important component of this. To this end, the Cluster for Research in Design and Sustainability (CRiDS) focuses its research energies towards developing resilient responses to the social, environmental and economic challenges associated with urbanism and cities, in both the developed and developing world.

Explore all the Open Access research of the Department of Architecture. Or explore all of Strathclyde's Open Access research...

Two-degree-of-freedom VIV of circular cylinder with variable natural frequency ratio : experimental and numerical investigations

Srinil, Narakorn and Zanganeh, Hossein and Day, Alexander (2013) Two-degree-of-freedom VIV of circular cylinder with variable natural frequency ratio : experimental and numerical investigations. Ocean Engineering, 73. pp. 179-194. ISSN 0029-8018

[img] PDF (OE2013NS-HZ-AD)
OE2013_NS_HZ_AD.pdf
Preprint

Download (2MB)

Abstract

Slender offshore structures possess multiple natural frequencies in different directions which can lead to different resonance conditions when undergoing vortex-induced vibration (VIV). This paper presents an experimental and numerical investigation of a two-degree-of-freedom VIV of a flexibly mounted circular cylinder with variable in-line-to-cross-flow natural frequency ratio. A mechanical spring-cylinder system, achieving a low equivalent mass ratio in both in-line and cross-flow directions, is tested in a water towing tank and subject to a uniform steady flow in a sub-critical Reynolds number range of about 2×103–5×104. A generalized numerical prediction model is based on the calibrated Duffing-van der Pol (structure-wake) oscillators which can capture the structural geometrical coupling and fluid-structure interaction effects through system cubic and quadratic nonlinearities. Experimental results for six measurement datasets are compared with numerical results in terms of response amplitudes, lock-in ranges, oscillation frequencies, time-varying trajectories and phase differences of cross-flow/in-line motions. Some good qualitative agreements are found which encourage the use of the implemented numerical model subject to calibration and the sensitivity analysis of empirical coefficients. Moreover, comparisons of the newly-obtained and published experimental results are carried out and discussed, highlighting a good correspondence in both amplitude and frequency responses. Various patterns of figure-of-eight orbital motions associated with dual two-to-one resonances are observed experimentally as well as numerically: the forms of trajectories are noticed to depend on the system mass ratio, damping ratio, reduced velocity parameter and natural frequency ratio of the two-dimensional oscillating cylinder.