The Dynamics of Non-Spherical Particles. Part II. Mobility in Non-Orienting Fields

The Dynamics of Non-Spherical Particles. Part II. Mobility in Non-Orienting Fields PDF Author: Isaiah Gallily
Publisher:
ISBN:
Category :
Languages : en
Pages : 115

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Book Description
This report presents the stochastic nature of the mobility of aerosol particles in non-orienting fields of force. A dynamic model for the interaction between particles' translation and Brownian rotation was assumed and a Monte Carlo method applied to compute the distribution of particles' (verticle) trajectories. The distribution was calculated for several particle shapes, various geometric dimensions, various total times of motion, and various initial orientations. From the calculations it was seen that the aerodynamic diameter is actually a statistical parameter, which should be taken into account. On the experimental side, the principal translational coefficients of cylindrical glass fibers was determined with the aid of a special apparatus and technique. Fibers' dimensions were found according to a previously developed photogrammetric method, employing a scanning electron microscope.

The Dynamics of Non-Spherical Particles. Part II. Mobility in Non-Orienting Fields

The Dynamics of Non-Spherical Particles. Part II. Mobility in Non-Orienting Fields PDF Author: Isaiah Gallily
Publisher:
ISBN:
Category :
Languages : en
Pages : 115

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Book Description
This report presents the stochastic nature of the mobility of aerosol particles in non-orienting fields of force. A dynamic model for the interaction between particles' translation and Brownian rotation was assumed and a Monte Carlo method applied to compute the distribution of particles' (verticle) trajectories. The distribution was calculated for several particle shapes, various geometric dimensions, various total times of motion, and various initial orientations. From the calculations it was seen that the aerodynamic diameter is actually a statistical parameter, which should be taken into account. On the experimental side, the principal translational coefficients of cylindrical glass fibers was determined with the aid of a special apparatus and technique. Fibers' dimensions were found according to a previously developed photogrammetric method, employing a scanning electron microscope.

Microscale Dynamics in Suspensions of Non-spherical Particles

Microscale Dynamics in Suspensions of Non-spherical Particles PDF Author: Amit Kumar
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Numerical simulations were performed to investigate the microscale dynamics in suspensions of spherical and non-spherical particles. Two new algorithms were developed to enable studies with accurate hydrodynamics. The first algorithm was a high accuracy Stokesian Dynamics technique (SD) extended to a generic non-spherical particle shape. The many body interactions were computed using a novel scheme employing one body singularity solutions. Near field lubrication interactions employed standard asymptotic solutions for nearly touching convex particles. The second algorithm was a reduced precision near-field lubrication based method called Fast Lubrication Dynamics (FLD). In addition to the near field interactions, we introduced a novel isotropic resistance in FLD to match the mean particle mobility from the more detailed SD. The resulting FLD algorithm was shown to give results comparable to that from the detailed SD, while requiring only a fraction of the latter's computational expense. In a first series of studies using the SD technique, we computed the transport properties in equilibrium suspensions of spheres and dicolloids. The latter particle shape was modeled as two intersecting spheres of varying radii and center to center separations. It was found that the infinite frequency viscosity as well as the short-time translational self-diffusivity are non-monotonic function of aspect ratio at any given non-dilute volume fraction with the minima in viscosity and the maxima in self-diffusivity around an aspect of 1.5. In contrast, the short-time rotational self-diffusivity was found to be a monotonically decreasing function of the aspect ratio at any given volume fraction. In a second series of studies using the SD technique we investigated the microstructure, orientation, and rheology in suspensions of spheres and dicolloids over a wide range of volume fractions $0 leq phi leq 0.55$. The particles had a very short range repulsive interparticle interaction. The microstructure in suspensions of all particle shapes was found to be disordered for volume fractions $phi leq 0.5$, while a string like ordering was observed in suspensions of spheres and other particles with small degree of anisotropy at $phi=0.55$. Both the first and the second normal stress differences were negative for volume fractions up to $phi=0.5$, but some were positive at the highest volume fraction studied here ($phi=0.55$). The orientation behavior was found to be a function of both the fore-aft symmetry and the degree of anisotropy. For particles with fore-aft symmetry, in comparison to infinite dilution, a shift to higher orbit constants (increased alignment in the flow-gradient plane) was observed at low volume fractions. On the other hand, the particle lacking fore-aft symmetry showed virtually no change in its orientation distribution at low volume fractions. At higher volume fractions ($phi geq 0.2$), in comparison to the dilute suspensions, a shift towards lower orbit constants (increased alignment with the vorticity axis) was observed for all particle shapes. The degree of this alignment was found to increase with volume fraction for particles with small degree of anisotropy, while it was found to plateau at relatively low volume fractions in suspensions of particles with the largest degree of anisotropy. The observed orientation behavior was explained using a novel analysis technique based on the coupling of particle's angular velocity and hydrodynamic stresslet through the mobility tensor. Next, we investigated microstructure and orientation in Brownian suspensions of spheres and dicolloids using the FLD algorithm. Results are reported for two different volume fractions, $phi=42%$ and $phi=55%$. The 42% sample had a long range repulsive electrostatic interaction, while the 55% sample had hard-sphere type interaction. Particles with small degree of anisotropy showed microstructural transitions similar to that of spheres. In contrast, particles with relatively larger degree of anisotropy showed a significantly different microstructural behavior. At low shear rates, irrespective of the degree of anisotropy, an orientationally disordered state was observed. Upon further increase in the rate of shear, an increase in flow alignment is obtained, with the maximum flow alignment typically observed between $Pe=1$ and $Pe=20$ depending on the particle shape. With a further increase in the rate of shear, an increase in vorticity alignment is seen for all particle shapes. The degree of anisotropy and volume fraction was found to have a significant impact on the extent of increase in the flow or the vorticity alignment. Using FLD simulations we next investigated the phase behavior and rheology in charged colloidal suspensions at a volume fraction of $phi=0.33$. It was shown that for a given screening length of the repulsive interaction, there existed a range of surface potentials for which both the ordered and disordered metastable states exist. This range was found to have a strong dependence on shear rate and was found to have a maximum width around $Pe = 0.5$, where $Pe = dot{gamma}a^2/D_0$. The presence of both the ordered and disordered metastable states allowed us to simultaneously characterize both the branches of viscosity as a function of shear rate. It was observed that the disordered branch can have a lower viscosity than the ordered branch at low shear rates ($Pe

Current Awareness in Particle Technology

Current Awareness in Particle Technology PDF Author:
Publisher:
ISBN:
Category : Particles
Languages : en
Pages : 386

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Microhydrodynamics

Microhydrodynamics PDF Author: Sangtae Kim
Publisher: Courier Corporation
ISBN: 0486317676
Category : Science
Languages : en
Pages : 546

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Book Description
"This book is well organized and comprehensive . . . an eloquent and enduring statement of significant hydrodynamic principles." — AIChE Journal Microhydrodynamics concerns the flow and related phenomena pertinent to the motion of small particles suspended in viscous fluids. This text focuses on determining the motion of a particle or particles through a viscous fluid in bounded and unbounded flow. Its central theme is the mobility relation between particle motion and forces. Microhydrodynamics: Principles and Selected Applications functions as a manual that explains methods for solving particulate flows at low-Reynolds number, from analytical to computational methods. The ever-increasing growth in computational power has resulted in a similar growth in the range of solvable problems in microhydrodynamics. Suitable for graduate students in engineering and applied mathematics, this text treats the mathematical foundations and highlights the interplay of both mathematical and physical insights, guiding readers through single particle theory and problems related to multiparticle analyses.

Government Reports Announcements & Index

Government Reports Announcements & Index PDF Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 272

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Government reports annual index

Government reports annual index PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1120

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Colloid and Interface Chemistry for Nanotechnology

Colloid and Interface Chemistry for Nanotechnology PDF Author: Peter Kralchevsky
Publisher: CRC Press
ISBN: 1466569050
Category : Science
Languages : en
Pages : 564

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Book Description
Colloid and interface science dealt with nanoscale objects for nearly a century before the term nanotechnology was coined. An interdisciplinary field, it bridges the macroscopic world and the small world of atoms and molecules. Colloid and Interface Chemistry for Nanotechnology is a collection of manuscripts reflecting the activities of research teams that have been involved in the networking project Colloid and Interface Chemistry for Nanotechnology (2006–2011), Action D43, the European Science Foundation. The project was a part of the intergovernmental framework for Cooperation in Science and Technology (COST), allowing the coordination of nationally funded research across Europe. With contributions by leading experts, this book covers a wide range of topics. Chapters are grouped into three sections: "Nanoparticle Synthesis and Characterization," "New Experimental Tools and Interpretation," and "Nanocolloidal Dispersions and Interfaces." The topics covered belong to six basic research areas: (1) The synthesis of nanostructured materials of well-defined size and function; (2) Analytical methods and tools for control and characterization of synthesized nanomaterials; (3) Self-assembly of nanomaterials, such as microemulsions and micelles, and their applications; (4) Bioinspired nanostructured materials—structure, properties, and applications; (5) Design of active, soft functional interfaces with unique properties for sensors, catalysts, and biomedical assays; and (6) Nanoscale elements in soft nanoscale devices for applications in analytical and biomedical sciences. This book describes highlights in nanotechnology based on state-of-the-art principles in colloid and interface science, demonstrating how great progress in the various branches of nanotechnology can be achieved. The application of these principles allows for the development of new experimental and theoretical tools.

Fluid Mechanics

Fluid Mechanics PDF Author: L D Landau
Publisher: Elsevier
ISBN: 1483140504
Category : Technology & Engineering
Languages : en
Pages : 549

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Book Description
Course of Theoretical Physics, Volume 6: Fluid Mechanics discusses several areas of concerns regarding fluid mechanics. The book provides a discussion on the phenomenon in fluid mechanics and their intercorrelations, such as heat transfer, diffusion in fluids, acoustics, theory of combustion, dynamics of superfluids, and relativistic fluid dynamics. The text will be of great interest to researchers whose work involves or concerns fluid mechanics.

Interfacial Electrokinetics and Electrophoresis

Interfacial Electrokinetics and Electrophoresis PDF Author: Angel V. Delgado
Publisher: CRC Press
ISBN: 9780824706036
Category : Science
Languages : en
Pages : 1018

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Book Description
Interfacial Electtrokinetics and Electrophoresis presents theoretical models and experimental procedures for the analysis of electrokinetic phenomena. It discusses the physics and chemistry of solid/liquid, liquid/liquid, and gas/liquid interfaces, and offers applications for the printing, environmental, pharmaceutical and biomedical industries.

Orientational Dynamics of Small Non-spherical Particles in Fluid Flows

Orientational Dynamics of Small Non-spherical Particles in Fluid Flows PDF Author:
Publisher:
ISBN: 9789163744730
Category :
Languages : en
Pages : 100

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Book Description