Simulation of vortex induced vibration of a bluff body structure

Understanding Vortex induced vibration (VIV) phenomenon is essential as it plays important role in designing marine risers which used in oil extraction from the seabed to the offshore platforms were exposed to external flows that may trigger dangerous VIV oscillations. The present two-dimensional nu...

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Main Author:	Malik Fesal, Siti Natasha
Format:	Thesis
Language:	English English English
Published:	2015
Subjects:	QA801-939 Analytic mechanics
Online Access:	http://eprints.uthm.edu.my/1486/2/SITI%20NATASHA%20MALIK%20FESAL%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/1486/1/24p%20SITI%20NATASHA%20MALIK%20FESAL.pdf http://eprints.uthm.edu.my/1486/3/SITI%20NATASHA%20MALIK%20FESAL%20WATERMARK.pdf
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spelling	my-uthm-ep.14862021-10-03T07:43:22Z Simulation of vortex induced vibration of a bluff body structure 2015-07 Malik Fesal, Siti Natasha QA801-939 Analytic mechanics Understanding Vortex induced vibration (VIV) phenomenon is essential as it plays important role in designing marine risers which used in oil extraction from the seabed to the offshore platforms were exposed to external flows that may trigger dangerous VIV oscillations. The present two-dimensional numerical simulations of circular bluff body is a continuation of previous efforts trying to study the effect of frequency and amplitudes of the cylinder oscillation that is confined in the cross-flow and inline flow separately. The k-ε turbulence model is used to simulate the turbulent flow to evaluate the drag and lift coefficient of circular towards the flow characteristics which used time independent test (transient) and tested at different Reynolds number between 10000 and 100000 with uniform velocities of 1.35m/s and 13.5m/s. Results from dynamic response of a cylinder bluff body vibrating at frequencies variation of 1.48 Hz, 2.77 Hz and 3 Hz within 0.3m, 0.5m and 0.7m amplitudes variation were observed in this study. It is shown that for inline flow, the vibration at 0.3m amplitude is significantly low for drag and lift coefficient value for Re at 100000 compared to Re at10000. Meanwhile for the cross flow value it is observed that gives high percentages with 39% of drag coefficient and with 59% of lift coefficient compare to inline flow at high amplitude. However at low mode amplitude the cross flow contributes more with 19% of drag coefficient and 11% for lift coefficient compare to inline flow. The result also show that the cylinder oscillate higher at frequency shedding value with higher magnitude for the cross flow compare to the inline flow. Consequently, in order to get better performance, the vortex modes in the wake of oscillating cylinder have been found to be dependent on the amplitude distribution along the length of the model. The results concludes that in order to avoid inevitable vibration it is advisable by increasing damping or splitter when designing marine riser to generate more stable vortex shedding frequency. 2015-07 Thesis http://eprints.uthm.edu.my/1486/ http://eprints.uthm.edu.my/1486/2/SITI%20NATASHA%20MALIK%20FESAL%20COPYRIGHT%20DECLARATION.pdf text en staffonly http://eprints.uthm.edu.my/1486/1/24p%20SITI%20NATASHA%20MALIK%20FESAL.pdf text en public http://eprints.uthm.edu.my/1486/3/SITI%20NATASHA%20MALIK%20FESAL%20WATERMARK.pdf text en validuser mphil masters Universiti Tun Hussein Onn Malaysia Faculty of Mechanical and Manufacturing Engineering
institution	Universiti Tun Hussein Onn Malaysia
collection	UTHM Institutional Repository
language	English English English
topic	QA801-939 Analytic mechanics
spellingShingle	QA801-939 Analytic mechanics Malik Fesal, Siti Natasha Simulation of vortex induced vibration of a bluff body structure
description	Understanding Vortex induced vibration (VIV) phenomenon is essential as it plays important role in designing marine risers which used in oil extraction from the seabed to the offshore platforms were exposed to external flows that may trigger dangerous VIV oscillations. The present two-dimensional numerical simulations of circular bluff body is a continuation of previous efforts trying to study the effect of frequency and amplitudes of the cylinder oscillation that is confined in the cross-flow and inline flow separately. The k-ε turbulence model is used to simulate the turbulent flow to evaluate the drag and lift coefficient of circular towards the flow characteristics which used time independent test (transient) and tested at different Reynolds number between 10000 and 100000 with uniform velocities of 1.35m/s and 13.5m/s. Results from dynamic response of a cylinder bluff body vibrating at frequencies variation of 1.48 Hz, 2.77 Hz and 3 Hz within 0.3m, 0.5m and 0.7m amplitudes variation were observed in this study. It is shown that for inline flow, the vibration at 0.3m amplitude is significantly low for drag and lift coefficient value for Re at 100000 compared to Re at10000. Meanwhile for the cross flow value it is observed that gives high percentages with 39% of drag coefficient and with 59% of lift coefficient compare to inline flow at high amplitude. However at low mode amplitude the cross flow contributes more with 19% of drag coefficient and 11% for lift coefficient compare to inline flow. The result also show that the cylinder oscillate higher at frequency shedding value with higher magnitude for the cross flow compare to the inline flow. Consequently, in order to get better performance, the vortex modes in the wake of oscillating cylinder have been found to be dependent on the amplitude distribution along the length of the model. The results concludes that in order to avoid inevitable vibration it is advisable by increasing damping or splitter when designing marine riser to generate more stable vortex shedding frequency.
format	Thesis
qualification_name	Master of Philosophy (M.Phil.)
qualification_level	Master's degree
author	Malik Fesal, Siti Natasha
author_facet	Malik Fesal, Siti Natasha
author_sort	Malik Fesal, Siti Natasha
title	Simulation of vortex induced vibration of a bluff body structure
title_short	Simulation of vortex induced vibration of a bluff body structure
title_full	Simulation of vortex induced vibration of a bluff body structure
title_fullStr	Simulation of vortex induced vibration of a bluff body structure
title_full_unstemmed	Simulation of vortex induced vibration of a bluff body structure
title_sort	simulation of vortex induced vibration of a bluff body structure
granting_institution	Universiti Tun Hussein Onn Malaysia
granting_department	Faculty of Mechanical and Manufacturing Engineering
publishDate	2015
url	http://eprints.uthm.edu.my/1486/2/SITI%20NATASHA%20MALIK%20FESAL%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/1486/1/24p%20SITI%20NATASHA%20MALIK%20FESAL.pdf http://eprints.uthm.edu.my/1486/3/SITI%20NATASHA%20MALIK%20FESAL%20WATERMARK.pdf
_version_	1747830800559112192

Simulation of vortex induced vibration of a bluff body structure

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