An Analytical Mechanics Framework for Flow-Oscillator Modeling of Vortex-Induced Bluff-Body Oscillations
An Analytical Mechanics Framework for Flow-Oscillator Modeling of Vortex-Induced Bluff-Body Oscillations

Author: Sohrob Mottaghi

Publisher:

Published: 2020

Total Pages: 245

ISBN-13: 9783030261320

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This self-contained book provides an introduction to the flow-oscillator modeling of vortex-induced bluff-body oscillations. One of the great challenges in engineering science also happens to be one of engineering design - the modeling, analysis and design of vibrating structures driven by fluid motion. The literature on fluid-structure interaction is vast, and it can be said to comprise a large fraction of all papers published in the mechanical sciences. This book focuses on the vortex-induced oscillations of an immersed body, since, although the importance of the subject has long been known, it is only during the past fifty years that there have been concerted efforts to analytically model the general behavior of the coupling between vortex shedding and structural oscillations. At the same time, experimentalists have been gathering data on such interactions in order to help define the various regimes of behavior. This data is critical to our understanding and to those who develop analytical models, as can be seen in this book. The fundamental bases for the modeling developed in this book are the variational principles of analytical dynamics, in particular Hamilton's principle and Jourdain's principle, considered great intellectual achievements on par with Newton's laws of motion. Variational principles have been applied in numerous disciplines, including dynamics, optics and quantum mechanics. Here, we apply variational principles to the development of a framework for the modeling of flow-oscillator models of vortex-induced oscillations.

An Analytical Mechanics Framework for Flow-Oscillator Modeling of Vortex-Induced Bluff-Body Oscillations
An Analytical Mechanics Framework for Flow-Oscillator Modeling of Vortex-Induced Bluff-Body Oscillations

Author: Sohrob Mottaghi

Publisher: Springer

Published: 2019-08-08

Total Pages: 245

ISBN-13: 3030261336

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This self-contained book provides an introduction to the flow-oscillator modeling of vortex-induced bluff-body oscillations. One of the great challenges in engineering science also happens to be one of engineering design – the modeling, analysis and design of vibrating structures driven by fluid motion. The literature on fluid–structure interaction is vast, and it can be said to comprise a large fraction of all papers published in the mechanical sciences. This book focuses on the vortex-induced oscillations of an immersed body, since, although the importance of the subject has long been known, it is only during the past fifty years that there have been concerted efforts to analytically model the general behavior of the coupling between vortex shedding and structural oscillations. At the same time, experimentalists have been gathering data on such interactions in order to help define the various regimes of behavior. This data is critical to our understanding and to those who develop analytical models, as can be seen in this book. The fundamental bases for the modeling developed in this book are the variational principles of analytical dynamics, in particular Hamilton’s principle and Jourdain’s principle, considered great intellectual achievements on par with Newton’s laws of motion. Variational principles have been applied in numerous disciplines, including dynamics, optics and quantum mechanics. Here, we apply variational principles to the development of a framework for the modeling of flow-oscillator models of vortex-induced oscillations.

Mechanics of Flow-Induced Vibration
Mechanics of Flow-Induced Vibration

Author: Rajeev Jaiman

Publisher: Springer Nature

Published: 2023-06-10

Total Pages: 1028

ISBN-13: 9811985782

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This book discusses various passive and active techniques for controlling unsteady flow dynamics and associated coupled mechanics of fluid-structure interaction. Coupled multiphysics and multidomain simulations are emerging and challenging research areas, which have received significant attention during the past decade. One of the most common multiphysics and multidomain problems is fluid-structure interaction (FSI), i.e., the study of coupled physical systems involving fluid and a structure that have a mechanical influence on each other. Regardless of the application area, the investigation toward modeling of fluid-structure interaction and the underlying mechanisms in dealing with coupled fluid-structure instability with real-world applications remains a challenge to scientists and engineers. This book is designed for students and researchers who seek knowledge of computational modeling and control strategies for fluid-structure interaction. Specifically, this book provides a comprehensive review of the underlying unsteady physics and coupled mechanical aspects of the fluid-structure interaction of freely vibrating bluff bodies, the self-induced flapping of thin flexible structures, and aeroelasticity of shell structures. Understanding flow-induced loads and vibrations can lead to safer and cost-effective structures, especially for light and high-aspect ratio structures with increased flexibility and harsh environmental conditions. Using the body-fitted and moving mesh formulations, the physical insights associated with structure-to-fluid mass ratios, Reynolds number, nonlinear structural deformation, proximity interference, near-wall contacts, free-surface, and other interacting physical fields are covered in this book. In conjunction with the control techniques, data-driven model reduction approaches based on subspace projection and deep neural calculus are covered for low-dimensional modeling of unsteady fluid-structure interaction.

Study of Reduced Order Models for Vortex-induced Vibration and Comparison with CFD Results
Study of Reduced Order Models for Vortex-induced Vibration and Comparison with CFD Results

Author: Christopher W. Olenek

Publisher:

Published: 2011

Total Pages:

ISBN-13:

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Vortex-induced vibration (VIV) is a dynamic phenomenon that can occur when there is fluid flow past a bluff body with flexibility. Over time, VIV can cause fatigue damage, so it may be desirable to suppress these vibrations. It is important to understand how the system behaves when trying to control vibrations; a reduced order model may be an effective way to study the system dynamics. Developing a data driven model from simulation and/or experimental results can be difficult, but there are existing phenomenological models that attempt to describe VIV, several of which will be explored in this thesis. These models consist of a structural equation representing a simple sprung bluff body coupled to a wake equation representing the effects of the surrounding fluid on the oscillator; the latter is generally a nonlinear oscillator exhibiting limit cycle behavior. The coupling, structural equation, and type of nonlinearity in the wake equation vary between different models, and the effects of these differences will be explored. The parameters of these equations must be identified, and then results from these models will be compared with the results obtained from a high fidelity CFD simulation to determine the relative quality of each reduced order model. The deficiencies of each model and the effects they produce will also be explored. Finally, the most important traits of each reduced order model will be identified, and, finally, the best reduced order model, with specific parameter values, will be presented.

Modeling of Vortex-Induced Oscillations Based on Indicial Response Approach
Modeling of Vortex-Induced Oscillations Based on Indicial Response Approach

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-07-05

Total Pages: 32

ISBN-13: 9781722381257

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The indicial response approach, a modeling approach originally used for studying nonlinear problems in flight dynamics is applied to the study of vortex-induced oscillations phenomena. The indicial response of the velocity field is derived for the problem studied with emphasis on physical postulates involved. A full account of fluid dynamics effects is taken by considering the incompressible Navier-Stokes equations. The theory is applied to the particular case of flow past a cylinder in periodically forced motion to derive some salient features. The indicial response approach is shown to be equivalent to a currently popular approach based on the use of the amplitude equation. Jump and hysteresis phenomena that experiments indicate occur within the lock-in regime (where the velocity field oscillates at the forcing frequency) are captured by the approach. Truong, Khiem Van Unspecified Center NCC2-634...

Piezoelectric Energy Harvesting
Piezoelectric Energy Harvesting

Author: Alper Erturk

Publisher: John Wiley & Sons

Published: 2011-04-04

Total Pages: 377

ISBN-13: 1119991358

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The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

Vortex Induced Vibrations
Vortex Induced Vibrations

Author: Vijay Matheswaran

Publisher:

Published: 2022

Total Pages: 0

ISBN-13:

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Vortex shedding and Vortex Induced Vibrations (VIV) of bluff bodies is a fundamental problem in fluid mechanics. The ubiquity of vortex shedding and VIV in several engineering fields has meant that a significant amount of research has centered on this subject. Recent studies have focused on the extraction of energy from steady flow using bodies undergoing VIV. In this dissertation, a new model for flow around a circular cylinder called the Hybrid Potential Flow (HPF) model is presented. The HPF model incorporates potential flow methods, experimental data and von Karman’s representation of the vortex wake to construct a complete solution for flow around a circular cylinder in the sub-critical Reynolds number regime $300 \leq Re \leq 1.5 x 10^5).$ Shedding frequencies and forces due to vortex shedding are calculated and compared to published results. The HPF model is extended to other bluff body geometries using conformal mapping. A composition of Karman-Trefftz transformations and Fornberg’s method is used to construct a conformal map between the physical domain and the circle plane. The combination of the HPF model and conformal mapping can thus be used to quickly calculate vortex shedding behavior for various bluff bodies. Validation of theoretical results is done through experimental methods. A flow visualization technique to view the time-averaged wake behind bluff bodies is developed and presented. Wind tunnel tests are done to validate predicted shedding frequencies for various bluff body geometries. A proof-of-concept prototype of a device that extracts energy from steady flow using VIV is developed. Emphasis is laid on the device being of low cost and complexity. Finally, principal conclusions of this dissertation and recommendations for future work are presented.