Dynamic Simulation Of Flexible Fiber Suspensions

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Dynamic Simulation Of Flexible Fiber Suspensions

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Author : Russell F. Ross
language : en
Publisher:
Release Date : 1996

Dynamic Simulation Of Flexible Fiber Suspensions written by Russell F. Ross and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.

Brownian Dynamics Simulation Of Flexible Fibers

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Author : Heiko Bette
language : en
Publisher:
Release Date : 2003

Brownian Dynamics Simulation Of Flexible Fibers written by Heiko Bette and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.

Simulation Of Flexible Fibers In Stokes Flow

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Author : Mohsan Jameel
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2011-12

Simulation Of Flexible Fibers In Stokes Flow written by Mohsan Jameel and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-12 with categories.

When elastic fibers are immersed in a Newtonian fluid, the behavior of the system, or the "fiber suspension" becomes non-Newtonian. Understanding the dynamics of such systems is of particular interest in a wide variety of fields, including locomotion of microorganisms, paper and pulp industry, microfluidics etc. When these fibers are immersed in the fluid at low Reynolds number, the elastic equation for the fibers couples to the Stokes equations, which greatly increases the computational complexity of the problem. I have simulated buckling behavior of a single fiber suspended in a shear flow and have applied two numerical method, a slender body approximation known as Local Drag model and a regularized Boundary Integral method known as Regularized Stokeslet method. We have extended the Local Drag model to simulate naturally bent fibers based on the target or resting curvature of the fibers. Microorganisms possess fiber-like organs known as the appendages and swim by flapping these organs. We have also simulated swimming motion of a simple microorganism model by imposing a time dependent resting curvature of these fibers.

Analysis Of Flexible Fiber Suspensions Using The Lattice Boltzmann Method

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Author : Sheila Rezak
language : en
Publisher:
Release Date : 2008

Analysis Of Flexible Fiber Suspensions Using The Lattice Boltzmann Method written by Sheila Rezak and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Fiber reclamation categories.

Results from simulation show the rigid fiber in simple shear flow produces a good agreement for orientation of a fiber relative to the theoretical study by Jeffery (1922). The flexible fiber exhibits an increase on the rotational period from the rigid fiber due to more deformation shape is revealed during rotation. The simulation technique demonstrates the ability to simulate fiber-fiber interactions to further study of relative viscosity of suspensions in shear flow. Simulation results show that fiber orientation and relative viscosity depend on the fiber characteristics (fiber aspect ratio, fiber flexibility, and volume fraction). The results are verified against known experimental measurements and theoretical results.

Direct Simulation Of Flexible Particle Suspensions Using Lattice Boltzmann Equation With External Boundary Force

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Author : Jingshu Wu
language : en
Publisher:
Release Date : 2010

Direct Simulation Of Flexible Particle Suspensions Using Lattice Boltzmann Equation With External Boundary Force written by Jingshu Wu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Deformations (Mechanics) categories.

Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in physical science. In general, the rheology of particle suspension is quite complex, and the problem becomes even more complicated if the suspending particle is deformable. Despite these difficulties, a large number of theoretical and experimental investigations have been devoted to the analysis and prediction of the rheological behavior of particle suspensions. However, among these studies there are very few investigations that focus on the role of particle deformability. A novel method for full coupling of the fluid-solid phases with sub-grid accuracy for the solid phase is developed. In this method, the flow is computed on a fixed regular 'lattice' using the lattice Boltzmann method (LBM), where each solid particle, or fiber, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the particle are obtained from Newtonian dynamics equations. The deformable particle is modeled by the lattice-spring model (LSM). The fiber deformation is calculated by an efficient flexible fiber model. The no-slip boundary condition at the fluid-solid interface is based on the external boundary force (EBF) method. This method is validated by comparing with known experimental and theoretical results.

Simulations Of Suspensions Of Brownian Spherocylinders And Non Brownian Linked Spherocylinders

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Author : Jing-Yao Chen (Ph.D.)
language : en
Publisher:
Release Date : 2020

Simulations Of Suspensions Of Brownian Spherocylinders And Non Brownian Linked Spherocylinders written by Jing-Yao Chen (Ph.D.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.

Fiber suspensions, both naturally occuring and synthetic, have many of applications, such as rheological modifiers and composite reinforcement. The rheological properties strongly depend on the microstructure, which varies with fiber properties, concentration, and processing methods. Rigid fiber suspensions form liquid crystalline phases. Flexible fiber suspensions form homogeneous networks and aggregates. In this thesis, fiber-level simulations were applied to systematically investigate the relationship between the microstructure and macroscopic properties, including the viscosity, normal stress differences, and diffusivities. Simulation programs were accelerated and parallelized for GPUs via CUDA. Rigid fibers were modeled as spherocylinders that interacted only through a soft repulsive force. Brownian dynamics simulations were employed to obtain the translational and rotational diffusivities, matching reported values of hard spherocylinder suspensions. Liquid crystalline phases, including nematic, smectic, and solid phases, were obtained. For suspensions that were isotropic at rest, flow curves, which contained two shear thinning regions bracketing a viscosity plateau at intermediate Pe̹clet numbers, qualitatively matched those for suspensions of cellulose nanocrystals. For suspensions that were nematic at rest, system-wide domains that aligned and kayaked about the vorticity direction, domains that rotated in the gradient direction, and layered domains were observed under shear. The transient rheological properties depended on the domain dynamics. Flexible fibers were modeled as spherocylinders that were connected by joints with bending and twisting potentials. The fibers were non-Brownian, and interacted through soft repulsion, short-ranged attraction, and friction. A drying and rehydration process was implemented. The volume fraction of the suspensions were raised 4 fold and subsequently lowered to the original value. The simulation box was shrunk and expanded with a constant number of fibers. During drying, the fibers were moved affinely after the equations of motion were integrated. When sufficient friction and attractive forces were applied, the viscosities for suspensions that were dried and rehydrated were lower than those for suspensions that were not dried and rehydrated. The reduction of viscosity was associated with the formation of dense and persistent flocs, which were observed experimentally for microfibrillated cellulose suspensions.

Simulations Of Suspensions Of Brownian Spherocylinders And Non Brownian Linked Spherocylinders

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Author : Jing-Yao Chen (Ph.D.)
language : en
Publisher:
Release Date : 2020

Simulations Of Suspensions Of Brownian Spherocylinders And Non Brownian Linked Spherocylinders written by Jing-Yao Chen (Ph.D.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.

Fiber suspensions, both naturally occuring and synthetic, have many of applications, such as rheological modifiers and composite reinforcement. The rheological properties strongly depend on the microstructure, which varies with fiber properties, concentration, and processing methods. Rigid fiber suspensions form liquid crystalline phases. Flexible fiber suspensions form homogeneous networks and aggregates. In this thesis, fiber-level simulations were applied to systematically investigate the relationship between the microstructure and macroscopic properties, including the viscosity, normal stress differences, and diffusivities. Simulation programs were accelerated and parallelized for GPUs via CUDA. Rigid fibers were modeled as spherocylinders that interacted only through a soft repulsive force. Brownian dynamics simulations were employed to obtain the translational and rotational diffusivities, matching reported values of hard spherocylinder suspensions. Liquid crystalline phases, including nematic, smectic, and solid phases, were obtained. For suspensions that were isotropic at rest, flow curves, which contained two shear thinning regions bracketing a viscosity plateau at intermediate Pe̹clet numbers, qualitatively matched those for suspensions of cellulose nanocrystals. For suspensions that were nematic at rest, system-wide domains that aligned and kayaked about the vorticity direction, domains that rotated in the gradient direction, and layered domains were observed under shear. The transient rheological properties depended on the domain dynamics. Flexible fibers were modeled as spherocylinders that were connected by joints with bending and twisting potentials. The fibers were non-Brownian, and interacted through soft repulsion, short-ranged attraction, and friction. A drying and rehydration process was implemented. The volume fraction of the suspensions were raised 4 fold and subsequently lowered to the original value. The simulation box was shrunk and expanded with a constant number of fibers. During drying, the fibers were moved affinely after the equations of motion were integrated. When sufficient friction and attractive forces were applied, the viscosities for suspensions that were dried and rehydrated were lower than those for suspensions that were not dried and rehydrated. The reduction of viscosity was associated with the formation of dense and persistent flocs, which were observed experimentally for microfibrillated cellulose suspensions.

Dynamic Simulations Of Electro And Magnetorheological Fiber Suspensions

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Author : Wee Teck William Ho
language : en
Publisher:
Release Date : 2010

Dynamic Simulations Of Electro And Magnetorheological Fiber Suspensions written by Wee Teck William Ho and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.

The Effect Of Flexibility On Interaction Of Two Fibers Settling In Moderate Reynolds Numbers

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Author : Ahmed Alhasan
language : en
Publisher:
Release Date : 2016

The Effect Of Flexibility On Interaction Of Two Fibers Settling In Moderate Reynolds Numbers written by Ahmed Alhasan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Fibers categories.

The behavior of solid particles in a fluid has become an important topic. The need to improve our understanding of the mechanisms of fluid-particle interaction is the motivation for the present work. The characteristics of fibers suspensions depend on the many variables such as flexibility, Reynolds numbers, density and aspect ratio. The aim of this work is to probe effects of these variables on sedimentation behavior by using a fiber-level simulation technique. In this techniques, a D3Q15 model in a lattice Boltzmann equation with a Bhatnagar-Gross-Krook (BGK) approximation is used to simulate motion of fluids, where Navier-Stokes equations are solved equivalently. Meanwhile, a lattice spring model is utilized to mimic the deformation of flexible fibers. The interaction between fluid and solid fiber is handled by an immersed boundary method. Dynamic motion of a single flexible fiber and two flexible fibers settling in an infinite long fluid column at low and moderate Reynolds numbers are numerically simulated in a three dimensional space. The fiber flexibility and density are varied at different levels and their effects on sedimentation are studied. In the simulations, cuboid and cylindrical fibers at different aspect ratios are considered. It is demonstrated that the fiber flexibility has an important impact on fiber position, settling velocities, and fluid structures, where the drafting, kissing, and tumbling (DKT) mechanisms play important roles. The simulation results provide useful information, at a microscopic level, which may not be easily measured in a lab environment.

Rheology

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Author : Juan De Vicente
language : en
Publisher: BoD – Books on Demand
Release Date : 2012-03-07

Rheology written by Juan De Vicente and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-03-07 with Science categories.

This book contains a wealth of useful information on current rheology research. By covering a broad variety of rheology-related topics, this e-book is addressed to a wide spectrum of academic and applied researchers and scientists but it could also prove useful to industry specialists. The subject areas include, polymer gels, food rheology, drilling fluids and liquid crystals among others.