Simulation of Lateral Migration and Sedimentation of a Flexible Fiber in a Vertical Weak Shear Flow
Title | Simulation of Lateral Migration and Sedimentation of a Flexible Fiber in a Vertical Weak Shear Flow PDF eBook |
Author | Ali Ibrahim Neamah Neamah |
Publisher | |
Pages | 58 |
Release | 2015 |
Genre | |
ISBN |
This research is a thorough numerical investigation and critical analysis of lateral migration of a deformable particle settling in a vertical weak shear flow. Under the vertical weak shear fluid, the deformable particle may move either to the coagulation area, or the dispersion area, depending on Reynolds numbers, shear Reynolds number, fiber flexibility, and aspect ratio. In this study, a lattice Boltzmann equation is used to solve Navier-Stokes equation and a flexible particle method is employed to attack the problem of motion of a flexible fiber. A bounce-back rule is used to deal with moving boundaries interacting with fluids. Several simulations are first conducted at the same shear Reynolds number, particle settling Reynolds number and aspect ratio except that the rigidity is varied at different levels. It is found that the rigidity plays a critical role, may change particle lateral migration direction, either migrate toward a coagulation area, or toward a dispersion area, depending the value of the rigidity. It shows that the rigidity may alter the fiber inertia, in turn, convert coagulation to dispersion. In other words, flexibility may alter the stability of fiber suspension. At a low settling Reynolds number, as the vertical shear flow increases the fiber dispersion trend increases and the lower rigid fiber has a larger tendency to disperse.
Simulation of Flexible Fibers in Stokes Flow
Title | Simulation of Flexible Fibers in Stokes Flow PDF eBook |
Author | Mohsan Jameel |
Publisher | LAP Lambert Academic Publishing |
Pages | 92 |
Release | 2011-12 |
Genre | |
ISBN | 9783847315575 |
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
Title | Analysis of Flexible Fiber Suspensions Using the Lattice Boltzmann Method PDF eBook |
Author | Sheila Rezak |
Publisher | |
Pages | |
Release | 2008 |
Genre | Fiber reclamation |
ISBN |
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.
Simulations of Flocculation in Flowing Fiber Suspensions
Title | Simulations of Flocculation in Flowing Fiber Suspensions PDF eBook |
Author | Christian Frederick Schmid |
Publisher | |
Pages | 252 |
Release | 1999 |
Genre | |
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Lateral Migration of a Solid Particle in Shear Flow
Title | Lateral Migration of a Solid Particle in Shear Flow PDF eBook |
Author | Wutthapong Jiraporncharoen |
Publisher | |
Pages | 82 |
Release | 2001 |
Genre | Fluid dynamics |
ISBN |
Numerical Study of Flow in Three-dimensional Fiber Networks and Sedimentation of Curved Fiber by Lattice Boltzmann Method
Title | Numerical Study of Flow in Three-dimensional Fiber Networks and Sedimentation of Curved Fiber by Lattice Boltzmann Method PDF eBook |
Author | Xiaoying Rong |
Publisher | |
Pages | 73 |
Release | 2007 |
Genre | Chemical engineering |
ISBN | 9781109964882 |
Dynamic motions of fibers sedimenting and in shear flows are of great interest in the paper and pulp industry. Fibers are not just cylindrically shaped, but also curved. The sedimentation of curved fibers under gravity is studied. The aspect ratio, inertia of single curved fiber is found to affect the motion and orientation. Two and four fiber sedimentation under gravity are studied as well. The sedimentation of curved fiber is also compared with the sedimentation of cylindrical fiber. The curvature and position are found to affect the sedimentation of multiple fibers in Newtonain flow. The lattice Boltzmann method is employed in this study. The numerical simulation is focused on migration and rotation of curved fibers and the interactions between fibers.
Wall Effect on Lateral Migration of Spherical Particles in a Linear Shear Flow
Title | Wall Effect on Lateral Migration of Spherical Particles in a Linear Shear Flow PDF eBook |
Author | Ali Hamour |
Publisher | |
Pages | 334 |
Release | 1984 |
Genre | |
ISBN |