Viscoelastic Flow Instabilities
Author: Aaron Avagliano
Publisher:
Published: 1998
Total Pages: 450
ISBN-13:
DOWNLOAD EBOOKRead and Download eBook Full
Author: Aaron Avagliano
Publisher:
Published: 1998
Total Pages: 450
ISBN-13:
DOWNLOAD EBOOKAuthor: Jeffrey Alan Byars
Publisher:
Published: 1996
Total Pages: 249
ISBN-13:
DOWNLOAD EBOOKAuthor: Marios Avgousti
Publisher:
Published: 1992
Total Pages: 580
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DOWNLOAD EBOOKAuthor: Anne M. Grillet
Publisher:
Published: 1999
Total Pages: 486
ISBN-13:
DOWNLOAD EBOOKAuthor: Karkala Arun Kumar
Publisher:
Published: 2001
Total Pages: 278
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DOWNLOAD EBOOKAuthor: Helen Jane Wilson
Publisher:
Published: 1998
Total Pages:
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DOWNLOAD EBOOKAuthor: Boyang Qin
Publisher:
Published: 2018
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKThe flow of complex fluids, especially those containing polymers, is ubiquitous in nature and industry. From blood, plastic melts, to airway mucus, the presence of microstructures such as particles, proteins, and polymers, can impart nonlinear material properties not found in simple fluids like water. These rheological behaviors, in particular viscoelasticity, can give rise to flow anomalies found in industrial settings and intriguing transport dynamics in biological systems. The first part of my work focuses on the flow of viscoelastic fluids in physical systems. Here, I investigate the flow instabilities of viscoelastic fluids in three different geometries and configurations. Realized in microfluidic channels, these experiments mimic flows encountered in technology spanning the oil extraction, pharmaceutical, and chemical industries. In particular, by conducting high-speed velocimetry on the flow of polymeric fluid in a micro-channel, we report evidence of elastic turbulence in a parallel shear flow where the streamline is without curvature. These turbulent-like characteristics include activation of the flow at many time scales, anomalous increase in flow resistance, and enhanced mixing associated with the polymeric flow. Moreover, the spectral characteristics and spatial structures of the velocity fluctuations are different from that in a curved geometry. Measured using novel holographic particle tracking, Lagrangian trajectories show spanwise dispersion and modulations, akin to the traveling waves in the turbulent pipe flow of Newtonian fluids. These curvature perturbations far downstream can generate sufficient hoop stresses to sustain the flow instabilities in the parallel shear flow. The second part of the thesis focuses on the motility and transport of active swimmers in viscoelastic fluids that are relevant to biological systems and human health. In particular, by analyzing the swimming of the bi-flagellated green algae Chlamydomonas reinhardtii in viscoelastic fluid, we show that fluid elasticity enhances the flagellar beating frequency and the wave speed. Yet the net swimming speed of the alga is hindered for fluids that are sufficiently elastic. The origin of this complex response lies in the non-trivial change in flagellar gait due to elasticity. Numerical simulations show that such change in gait reduces elastic stress build up in the fluid and increases efficiency. These results further illustrate the complex coupling between fluid rheology and swimming gait in the motility of micro-organisms and other biological processes such as mucociliary clearance in mammalian airways.
Author: Deutsche Reichsbahn-Gesellschaft
Publisher:
Published: 2009
Total Pages: 179
ISBN-13:
DOWNLOAD EBOOKAuthor: Joel C. Miller
Publisher:
Published: 2006
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor: Michael Renardy
Publisher: SIAM
Published: 2000-01-01
Total Pages: 113
ISBN-13: 9780898719413
DOWNLOAD EBOOKThis monograph is based on a series of lectures presented at the 1999 NSF-CBMS Regional Research Conference on Mathematical Analysis of Viscoelastic Flows. It begins with an introduction to phenomena observed in viscoelastic flows, the formulation of mathematical equations to model such flows, and the behavior of various models in simple flows. It also discusses the asymptotics of the high Weissenberg limit, the analysis of flow instabilities, the equations of viscoelastic flows, jets and filaments and their breakup, as well as several other topics.