Analysis and Suppression of Instabilities in Viscoelastic Flows

Analysis and Suppression of Instabilities in Viscoelastic Flows PDF Author: Karkala Arun Kumar
Publisher:
ISBN:
Category :
Languages : en
Pages : 278

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Analysis and Suppression of Instabilities in Viscoelastic Flows

Analysis and Suppression of Instabilities in Viscoelastic Flows PDF Author: Karkala Arun Kumar
Publisher:
ISBN:
Category :
Languages : en
Pages : 278

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Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports PDF Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 484

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American Doctoral Dissertations

American Doctoral Dissertations PDF Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 816

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Applied Mechanics Reviews

Applied Mechanics Reviews PDF Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 528

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Nanoscale and Microscale Phenomena

Nanoscale and Microscale Phenomena PDF Author: Yogesh M. Joshi
Publisher: Springer
ISBN: 813222289X
Category : Technology & Engineering
Languages : en
Pages : 382

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Book Description
The book is an outcome of research work in the areas of nanotechnology, interfacial science, nano- and micro-fluidics and manufacturing, soft matter, and transport phenomena at nano- and micro-scales. The contributing authors represent prominent research groups from Indian Institute of Technology Bombay, Indian Institute of Technology Kanpur and Indian Institute of Science, Bangalore. The book has 13 chapters and the entire work presented in the chapters is based on research carried out over past three years. The chapters are designed with number of coloured illustrations, figures and tables. The book will be highly beneficial to academicians as well as industrial professionals working in the mentioned areas.

The Effects of Viscoelasticity on the Transitioning Cylinder Wake

The Effects of Viscoelasticity on the Transitioning Cylinder Wake PDF Author: David Hastings Richter
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 166

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Using a newly developed three dimensional, time dependent finite volume code designed to compute non-Newtonian flows over a large range of Reynolds number (Re), we performed simulations of viscoelastic flow past a circular cylinder. Our goal was to elucidate elastic effects during transition to turbulence in a bluff body wake. Based on its ability to capture essential physical processes in turbulent drag reduction studies, the FENE-P rheological model was employed in the calculation, and the numerical method utilized was such that a large range of rheological parameters (polymer length L, dimensionless Weissenberg number (Wi), and polymer concentration (beta) in the FENE-P model) could be probed. Simulations were performed for Reynolds numbers ranging from Re = 100 to Re = 3900. Within this range, the Newtonian cylinder wake first undergoes a series of secondary instabilities, transitioning the wake structure from a two-dimensional, laminar vortex shedding state to one exhibiting three-dimensional motion. This transition is characterized first by the mode A instability, which develops in the region of primary vortex development at a Reynolds number of Re = 190. The mode B instability then follows at Re = 260, resulting from unstable perturbation growth in the braid region between primary vortices. At still higher Reynolds numbers, Re = O(1000), the separated shear layer immediately behind the cylinder begins to transition prior to primary vortex shedding. Through nonlinear simulations as well as a Floquet linear stability analysis, viscoelasticity was observed to stabilize both regimes of three-dimensional transition. Full nonlinear simulations revealed that for high enough polymer extensibility L at Re = 300, where mode B instability structures dominate for Newtonian flow, the wake could be reverted back to a state resembling two-dimensional, laminar vortex shedding. This was then confirmed using a Floquet stability analysis, showing significantly suppressed growth rates for both the mode A and mode B instabilities in the linear regime of their development. Mechanisms of this stabilization are presented. At Re = 3900, viscoelasticity again stabilizes the flow, though at this point through a suppression of the Kelvin-Helmoltz rollup instability present in the separated shear layer for Newtonian flows. Once a primary Karman vortex is allowed to form without the influence of a transitioned shear layer, the wake then reverts back to one resembling the mode B instabilities. Confirming this, a study was then performed at the same Reynolds number but allowing for an inhomogeneous polymer concentration throughout the flow field. By injecting polymer additives on the upstream side of the cylinder, it was found that stabilization of the shear layer and of the subsequent wake could be achieved without the presence of polymeric stresses in all downstream locations of the flow.

Dissertation Abstracts International

Dissertation Abstracts International PDF Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 780

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Simulation of Material Processing: Theory, Methods and Application

Simulation of Material Processing: Theory, Methods and Application PDF Author: Ken-ichiro Mori
Publisher: CRC Press
ISBN: 9789026518225
Category : Technology & Engineering
Languages : en
Pages : 1170

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Book Description
This volume contains about 180 papers including seven keynotes presented at the 7th NUMIFORM Conference. It reflects the state-of-the-art of simulation of industrial forming processes such as rolling, forging, sheet metal forming, injection moulding and casting.

Hydrodynamics and Nonlinear Instabilities

Hydrodynamics and Nonlinear Instabilities PDF Author: Claude Godrèche
Publisher: Cambridge University Press
ISBN: 9780521017633
Category : Science
Languages : en
Pages : 700

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Book Description
This book presents five sets of pedagogical lectures by internationally respected researchers on nonlinear instabilities and the transition to turbulence in hydrodynamics. The book begins with a general introduction to hydrodynamics covering fluid properties, flow measurement, dimensional analysis and turbulence. Chapter two reviews the special characteristics of instabilities in open flows. Chapter three presents mathematical tools for multiscale analysis and asymptotic matching applied to the dynamics of fronts and localized nonlinear states. Chapter four gives a detailed review of pattern forming instabilities. The final chapter provides a detailed and comprehensive introduction to the instability of flames, shocks and detonations. Together, these lectures provide a thought-provoking overview of current research in this important area.

Theoretical and Applied Mechanics Report

Theoretical and Applied Mechanics Report PDF Author:
Publisher:
ISBN:
Category : Mechanics
Languages : en
Pages : 412

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