Download or read book Particle Dynamics in Turbulence written by Peter Dearborn Huck and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is well known for its ability to efficiently disperse matter, whether it be atmospheric pollutants or gasoline in combustion motors. Two considerations are fundamental when considering such situations. First, the underlying flow may have a strong influence of the behavior of the dispersed particles. Second, the local concentration of particles may enhance or impede the transport properties of turbulence. This dissertation addresses these points separately through the experimental study of two different turbulent flows. The first experimental device used is the so-called von K\'arm\'an flow which consists of an enclosed vessel filled with water that is forced by two counter rotating disks creating a strongly inhomogeneous and anisotropic turbulence. Two high-speed cameras permitted the creation a trajectory data base particles that were both isodense and heavier than water but were smaller than the smallest turbulent scales. The trajectories of this data base permitted a study of the turbulent kinetic energy budget which was shown to directly related to the transport properties of the turbulent flow. The heavy particles illustrate the role of flow anisotropy in the dispersive dynamics of particles dominated by effects related to their inertia. The second flow studied was a wind tunnel seeded with micrometer sized water droplets which was used to study the effects of local concentration of the settling velocities of these particles. A model based on theoretical multi-phase methods was developed in order to take into account the role of collective effects on sedimentation in a turbulent flow. The theoretical results emphasize the role of coupling between the underlying flow and the dispersed phase.

Download or read book Collective Dynamics of Particles written by Cristian Marchioli and published by Springer. This book was released on 2017-02-21 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book surveys the state-of-the-art methods that are currently available to model and simulate the presence of rigid particles in a fluid flow. For particles that are very small relative to the characteristic flow scales and move without interaction with other particles, effective equations of motion for particle tracking are formulated and applied (e.g. in gas-solid flows). For larger particles, for particles in liquid-solid flows and for particles that interact with each other or possibly modify the overall flow detailed model are presented. Special attention is given to the description of the approximate force coupling method (FCM) as a more general treatment for small particles, and derivations in the context of low Reynolds numbers for the particle motion as well as application at finite Reynolds numbers are provided. Other topics discussed in the book are the relation to higher resolution immersed boundary methods, possible extensions to non-spherical particles and examples of applications of such methods to dispersed multiphase flows.

Download or read book Particles in Wall Bounded Turbulent Flows Deposition Re Suspension and Agglomeration written by Jean-Pierre Minier and published by Springer. This book was released on 2016-07-26 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents an up-to-date review of turbulent two-phase flows with the dispersed phase, with an emphasis on the dynamics in the near-wall region. New insights to the flow physics are provided by direct numerical simuation and by fine experimental techniques. Also included are models of particle dynamics in wall-bounded turbulent flows, and a description of particle surface interactions including muti-layer deposition and re-suspension.

Download or read book Examination of Fluid particle Dynamics in Turbulent Non dilute Particle Suspension Flow written by Roberaldo Carvalho de Souza and published by . This book was released on 1981 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamics of Non spherical Particles in Turbulence written by Luis Blay Esteban and published by . This book was released on 2020 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book studies the dynamics of 2D objects moving through turbulent fluids. It examines the decay of turbulence over extended time scales, and compares the dynamics of non-spherical particles moving through still and turbulent fluids. The book begins with an introduction to the project, its aims, and its relevance for industrial applications. It then discusses the movement of planar particles in quiescent fluid, and presents the numerous methodologies used to measure it. The book also presents a detailed analysis of the falling style of irregular particles, which makes it possible to estimate particle trajectory and wake morphology based on frontal geometry. In turn, the book provides the results of an analysis of physically constrained decaying turbulence in a laboratory setting. These results suggest that large-scale cut-off in numerical simulations can result in severe bias in the computed turbulent kinetic energy for long waiting times. Combining the main text with a wealth of figures and sketches throughout, the book offers an accessible guide for all engineering students with a basic grasp of fluid mechanics, while the key findings will also be of interest to senior researchers.

Download or read book Turbulence and Particle Dynamics in Dense Crystal Slurries written by Andreas ten Cate and published by Delft University Press. This book was released on 2002 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents of this Doctoral Dissertation include: The microscopic modelling of hydrodynamics in industrial crystallizers, PIV experiments and lattice-Boltzmann simulations on a single sphere settling under gravity, Application of spectral forcing in lattice-Boltzmann simulations of homogeneous turbulence, Fully resolved simulations of colliding monodisperse spheres in forced isotropic turbulence, An assessment of fragmentation due to crystal-crystal collisions, Conclusions and Perspectives

Download or read book Particle Dynamics in Two phase Flows and Turbulence Theory written by Per-Arne Sundsbø and published by . This book was released on 1998* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Particle Dispersion in Isotropic Turbulence and Unsteady Particle Dynamics at Finite Reynolds Number written by Renwei Mei and published by . This book was released on 1990 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: A solution to particle dispersion in an isotropic turbulence under Stokes drag, Basset force and gravitational force is obtained in closed form using the independence approximation. The Basset force has no effect on the fluid velocity structure seen by the particles or the long-time particle diffusivities. It does affect the intensities of particle motion for particles with large settling rate and with response time comparable to the turbulence integral time scale. A solution for particles dispersion in isotropic turbulence with non-Stokesian drag and gravitational force is obtained. The time constants of the particle fluctuation in the directions parallel and perpendicular to the gravity are anisotropic. Turbulence increases particle response time constants and reduces settling velocity. Influence of the nonlinear drag, particle response time constants and settling rate on particle dispersion are investigated. Monte-Carlo simulations are performed for particle motions in an isotropic turbulence with non-Stokesian drag. Pseudo-turbulence is generated using random Fourier modes representation. Statistical averages are obtained from more than 5000 particles. The results of the simulation validate the preceeding analysis in the non-Stokesian drag range. The influence of turbulence structure on the dispersions of fluid and particle is examined. In addition to the integral length and time scales, the functional form of the energy spectrum is also important in describing the dispersions of both fluid and particles. Numerical solution for unsteady flow over a sphere indicates that the added-mass force at finite Reynolds number is the same as in the creeping flow and the potential flow. The classical Stokes solution is not valid at small frequency, $omega$, and the corresponding Basset force is proportional to $omega$, instead of $sqrt{omega}$. The Basset-force term has a kernel decays faster than (t- $tau$)$sp{-1/2}$ at large time. The use of the steady state drag coefficient with the instantaneous velocity is justified to approximate the quasi-steady drag on particles. Limiting behavior of the unsteady drag on a sphere at small frequency and low Reynolds number is obtained using matched asymptotic expansions. The modified Basset-force term at finite Re is constructed. It has a kernel decays as (t- $tau$)$sp{-2}$ at large times.

Download or read book Turbulence and Interactions written by Michel Deville and published by Springer Science & Business Media. This book was released on 2010-09-28 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains six keynote lectures and 44 contributed papers of the TI 2009 conference that was held in Saint-Luce, La Martinique, May 31-June 5, 2009. These lectures address the latest developments in direct numerical simulations, large eddy simulations, compressible turbulence, coherent structures, droplets, two-phase flows, etc. The present monograph is a snapshot of the state-of-the-art in the field of turbulence with a broad view on theory, experiments and numerical simulations.

Download or read book Effect of Particle Dynamics on Turbulence Measurements with the Laser Doppler Velocimeter written by R. H. Nichols and published by . This book was released on 1986 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical model for evaluating seed requirements for accurate turbulence measurements with the LV has been developed. A Monte Carlo turbulence model was developed which included an elementary description of the internal structure of an eddy. The model was applied to two simple turbulent flows, grid generated turbulence and a subsonic axisymmetric jet, to evaluate particle response and to establish particle size requirements for accurate LV measurements in these flows. Large monodisperse particles were found to cause the turbulence quantities to be underestimated, leading to a requirement for very small particles for meaningful turbulence measurements with the L.V. Rule of thumb criteria for particle size selection are developed. Keywords: Velocity data; Computer code; Turbulence measurements; laser velocimeter.

Download or read book The Effect of Particle Dynamics on Turbulence Measurements with the Laser Doopler Velocimeter written by Robert H. Nichols and published by . This book was released on 1986 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Particle Laden Flow written by Bernard Geurts and published by Springer Science & Business Media. This book was released on 2007-08-27 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a selection of the papers that were presented at the EUROMECH colloquium on particle-laden flow held at the University of Twente in 2006. The multiscale nature of this challenging field motivated the calling of the colloquium and reflects the central importance that the dispersion of particles in a flow has in various geophysical and environmental problems. The spreading of aerosols and soot in the air, the growth and dispersion of plankton blooms in seas and oceans, or the transport of sediment in rivers, estuaries and coastal regions are striking examples.

Download or read book Fluid particle Dynamics written by P. Uhlerr and published by . This book was released on 1965 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular and Particle Modelling of Laminar and Turbulent Flows written by Donald Greenspan and published by World Scientific. This book was released on 2005 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is the most fundamental and, simultaneously, the most complex form of fluid flow. However, because an understanding of turbulence requires an understanding of laminar flow, both are explored in this book.Groundwork is laid by careful delineation of the necessary physical, mathematical, and numerical requirements for the studies which follow, and include discussions of N-body problems, classical molecular mechanics, dynamical equations, and the leap frog formulas for very large systems of second order ordinary differential equations.Molecular systems are studied first in both two and three dimensions. Extension into the large is also of great interest, and it is for this purpose that we develop particle mechanics, which uses lump massing of molecules. All calculations are limited to a personal scientific computer, so that the methods can be utilized readily by others.

Download or read book Turbulent Particle Laden Gas Flows written by Aleksei Y. Varaksin and published by Springer Science & Business Media. This book was released on 2007-07-05 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents results of experimental and theoretical studies of "gas-solid particles" turbulent two-phase flows. It analyzes the characteristics of heterogeneous flows in channels (pipes), as well as those in the vicinity of the critical points of bodies subjected to flow and in the boundary layer developing on their surface. Coverage also treats in detail problems of physical simulation of turbulent gas flows which carry solid particles.

Download or read book Physical and Physiological Forest Ecology written by Pertti Hari and published by Springer Science & Business Media. This book was released on 2012-12-24 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces a holistic synthesis of carbon and nitrogen fluxes in forest ecosystems from cell to stand level during the lifetime of trees. Establishing that metabolism and physical phenomena give rise to concentration, pressure and temperature differences that generate the material and energy fluxes between living organisms and their environment. The editors and authors utilize physiological, physical and anatomical background information to formulate theoretical ideas dealing with the effects of the environment and the state of enzymes, membrane pumps and pigments on metabolism. The emergent properties play an important role in the transitions from detailed to more aggregate levels in the ecosystem. Conservation of mass and energy allow the construction of dynamic models of carbon and nitrogen fluxes and pools at various levels in the hierarchy of forest ecosystems.

Download or read book Computational Investigation of the Effects of Turbulence Inertia and Gravity on Particle Dynamics written by Peter John Ireland and published by . This book was released on 2015 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, we examine the motion of particles which are subjected to varying levels of turbulence, inertia, and gravity, in both homogeneous and inhomogeneous turbulence. These investigations are performed through direct numerical simulation (DNS) of the Eulerian fluid velocity field combined with Lagrangian particle tracking. The primary motivation of these investigations is to better understand and model the dynamics and growth of water droplets in warm, cumulus clouds. In the first part of this work, we discuss the code we developed for these simulations, Highly Parallel Particle-laden flow Solver for Turbulence Research (HiPPSTR). HiPPSTR uses efficient parallelization strategies, timeintegration techniques, and interpolation methods to enable massively parallel simulations of three-dimensional, particle-laden turbulence. In the second, third, and fourth sections of this work, we analyze simulations of particle-laden flows which are representative of those at the edges and cores of clouds. In the second section, we consider the mixing of droplets near interfaces with varying turbulence intensities and gravitational orientations, to provide insight into the dynamics near cloud edges. The simulations are parameterized to match windtunnel experiments of particle mixing which were conducted at Cornell, and the DNS and experimental results are compared and contrasted. Mixing is suppressed when turbulence intensities differ across the interface, and in all cases, the particle concentrations are subject to large fluctuations. In the third and fourth sections, we use HiPPSTR to analyze droplet motion in isotropic turbulence, which we take to be representative of adiabatic cloud cores. The third section examines the Reynolds-number scaling of single-particle and particle-pair statistics without gravity, while the fourth section shows results when gravity is included. While weakly inertial particles preferentially sample certain regions of the flow, gravity reduces the degree of preferential sampling by limiting the time particles can spend interacting the underlying turbulence. We find that when particle inertia is small, the particle relative velocities and radial distribution functions (RDFs) are almost entirely insensitive to the flow Reynolds number, both with and without gravity. The relative velocities and RDFs for larger particles tend to weakly depend on the Reynolds number and to strongly depend on the degree of gravity. While non-local, path-history interactions significantly affect the relative velocities of moderate and large particles without gravity, these interactions are suppressed by gravity, reducing the relative velocities. We provide a physical explanation for the trends in the relative velocities with Reynolds number and gravity, and use the model of [198] to understand and predict how the trends in the relative velocities will affect the RDFs. The collision kernels for particles representative of those in atmospheric clouds are generally seen to be independent of Reynolds number, both with and without gravity, indicating relatively low Reynolds-number simulations are able to capture much of the physics responsible for droplet collisions in clouds. We conclude by discussing practical implications of this work for the cloud physics and turbulence communities and suggesting areas for future research.