Download or read book Investigation of Particle Velocity and Drag with Spherical and Non spherical Particles Through a Backward Facing Step written by Kyle Frederick Larsen and published by . This book was released on 2007 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, a Phase Doppler Particle Analyzer (PDA) was used to measure gas and particle phase velocities in a backward facing step. The step produced a 2:1 increase in cross sectional area with a Reynolds number of 22,000 (based on step height) upstream of the step. Spherical particles of 1--10 mum with an average diameter of 4mum were used to measure the gas phase velocity. At least three sizes in the range of (38--212 mum) for four different particles shapes were studied. The shapes included: spheres, flakes, gravel, and cylinders. Since the PDPA is not able to measure the size of the non-spherical particles, the particles were first separated into size bins and a technique was developed using the PMT (photo multiplier tubes) gain to isolate the particle size of interest for each size measured. The same technique was also used to measure terminal velocities of the particles in quiescent air.

Download or read book The Kinematic Behavior of Spherical Particles in an Accelerating Environment written by Dean A. Wilson and published by . This book was released on 1970 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Particle turbulence Interaction in a Backward facing Step Flow written by Stanford University. Thermosciences Division. Thermosciences Division and published by . This book was released on 1995 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 1518 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Particle Dispersion with Spherical and Nonspherical Particles written by David Lee Black and published by . This book was released on 1997 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Behavior of Large Particles Falling in Quiescent Liquids written by G. E. Stringham and published by . This book was released on 1969 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Rotation and Translation of Non spherical Particles in Homogeneous Isotropic Turbulence written by Margaret Byron and published by . This book was released on 2015 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: The motion of particles suspended in environmental turbulence is relevant to many scientific fields, from sediment transport to biological interactions to underwater robotics. At very small scales and simple shapes, we are able to completely mathematically describe the motion of inertial particles; however, the motion of large aspherical particles is significantly more complex, and current computational models are inadequate for large or highly-resolved domains. Therefore, we seek to experimentally investigate the coupling between freely suspended particles and ambient turbulence. A better understanding of this coupling will inform not only engineering and physics, but the interactions between small aquatic organisms and their environments. In the following pages, we explore the roles of shape and buoyancy on the motion of passive particles in turbulence, and allow these particles to serve as models for meso-scale aquatic organisms. We fabricate cylindrical and spheroidal particles and suspend them in homogeneous, isotropic turbulence that is generated via randomly-actuated jet arrays. The particles are fabricated with agarose hydrogel, which is refractive-index-matched to the surrounding fluid (water). Both the fluid and the particle are seeded with passive tracers, allowing us to perform Particle Image Velocimetry (PIV) simultaneously on the particle and fluid phase. To investigate the effects of shape, particles are fabricated at varying aspect ratios; to investigate the effects of buoyancy, particles are fabricated at varying specific gravities. Each particle type is freely suspended at a volume fraction of [Phi]=0.1%, for which four-way coupling interactions are negligible. The suspended particles are imaged together with the surrounding fluid and analyzed using stereoscopic PIV, which yields three velocity components in a two-dimensional measurement plane. Using image thresholding, the results are separated into simultaneous fluid-phase and solid-phase velocity fields. Using these simultaneous measurements, we examine particles' turbulent slip velocity and compare it to particles' quiescent settling velocity, which we measure directly. We observe that the slip velocity is strongly reduced relative to the quiescent case, and explore various mechanisms of particle loitering in turbulence. We further explore the relationship between the instantaneous particle velocity and the instantaneous fluid velocity, and develop a linear parametrization. By comparing our experimental data to a simple one-dimensional flow in the context of this parametrization, we elucidate aspects of slip velocity that are unique to turbulence. We obtain the particles' angular velocity by applying the solid-body rotation equation to velocity measurements at points inside the particle. We find that the expected value of angular velocity magnitude does not vary significantly with particle aspect ratio, as long as particles are nearly neutrally buoyant. Stronger effects on rotation are found for more negatively-buoyant particles. We also investigate particles' inheritance of vorticity from turbulent velocity fields, and find that particle rotation can be predicted by applying a spatial filter to fluid-phase vorticity. The results of this study will allow us to more accurately predict the motion of aspherical particles, giving new insights into oceanic carbon cycling, industrial processes, and other important topics. This analysis will also shed light onto biological questions of navigation, reproduction, and predator-prey interaction by quantifying the turbulence-driven behavior of meso-scale aquatic organisms, allowing researchers to sift out passive vs. active effects in a behaving organism. Lastly, processes that are directly dependent on particle dynamics (e.g., sediment transport, industrial processes) will be informed by our results.

Download or read book The dynamics of finite size settling particles written by Doychev, Todor and published by KIT Scientific Publishing. This book was released on 2015-01-27 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contributes to the fundamental understanding of the physical mechanisms that take place in pseudo turbulent particulate flows. In the present work we have considered the sedimentation of large numbers of spherical rigid particles in an initially quiescent flow field. We have performed direct numerical simulations employing an immersed boundary method for the representation of the fluid-solid interface. The results evidence that depending on the particle settling regime (i.e. Galileo number and particle-to-fluid density ratio) the particles may exhibit strong inhomogeneous spatial distribution. It is found that the particles are preferentially located in regions with downward fluid motion. The particles inside clusters experience larger settling velocities than the average. The flow in all flow cases is observed to exhibit characteristic features of pseudo-turbulence. The particle-induced flow field is further found to be highly anisotropic with dominant vertical components. The results indicate that, in the present flow configurations, the collective and mobility effects play significant role for the particle and fluid motion.

Download or read book The Kinematic Behavior of Spherical Particles in an Accelerating Environment written by Dean A. Wilson (Geophysicist) and published by . This book was released on 1970 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of a spherical particle to an accelerating environment is investigated. When the Reynolds numbers associated with such accelerations are small, the particle is in Stokes' regime and the linear equations governing its motion can be solved analytically. Outside Stokes' regime, which is the general case for spheres comparable in size to precipitation particles, the equations are nonlinear and must be solved numerically.The numerical solution indicates that particles of all sizes falling in a sheared environment are excellent tracers of the mean air motion. Even a hailstone as large as 2 cm in diameter falling at its terminal speed can be expected to follow the mean horizontal air speed within +/- 0.5 m sec -1, provided the vertical wind shear is less than 10 -2 sec 1. However, the time response of a spherical particle to a wind gust of constant velocity is quite sensitive to particle size. This response can be approximated by an expression of the form 1 e -t/[tau] where t depends on both particle size and the magnitude of the wind gust. For wind gusts of 1.0 m sec -1, [tau] is seen to vary from less than 10 -5 sec for particles smaller than 0.02 mm in diameter to 2.5 sec for a 2.0-cm hailstone. Also, when a particle is submitted to a substantial wind gust, a significant decrease in its terminal velocity occurs.It is suggested that the response of a nonspherical particle to wind accelerations will be at least as fast as this study indicates for a spherical particle of the same mass .

Download or read book Advanced Numerical Modelling of Wave Structure Interaction written by David M Kelly and published by CRC Press. This book was released on 2021-04-06 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will serve as a reference guide, and state-of-the-art review, for the wide spectrum of numerical models and computational techniques available to solve some of the most challenging problems in coastal engineering. The topics covered in this book, are explained fundamentally from a numerical perspective and also include practical examples applications. Important classic themes such as wave generation, propagation and breaking, turbulence modelling and sediment transport are complemented by hot topics such as fluid and structure interaction or multi-body interaction to provide an integral overview on numerical techniques for coastal engineering. Through the vision of 10 high impact authors, each an expert in one or more of the fields included in this work, the chapters offer a broad perspective providing several different approaches, which the readers can compare critically to select the most suitable for their needs. Advanced Numerical Modelling of Wave Structure Interaction will be useful for a wide audience, including PhD students, research scientists, numerical model developers and coastal engineering consultants alike.

Download or read book Air Force Research Resum s written by and published by . This book was released on with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Generalized Drag Coefficient Reynolds Number Plot for Non spherical Particles written by Paul Shang-hsien Chow and published by . This book was released on 1964 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Drag Forces written by Douglas G. Boike and published by . This book was released on 1977 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1983 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Particle Drag Coefficient on Particle Motion in High speed Flow with Typical Laser Velocimeter Applications written by Michael J. Walsh and published by . This book was released on 1976 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Dynamics of Non spherical Particles 1 Controlled Generation of Non spherical Aerosols and Methods for Their Size Concentration and Electric Charge Measurement written by Isaiah Gallily and published by . This book was released on 1974 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The typical features of the motion of a nonspherical aerosol particle are discussed, an overall aim concerning its behavior in systems of importance for human environment is stated and a preliminary objective of studying methods for generation, size measurement, determination of concentration and assessment of electric charge is set. Previous investigations in these lines are reviewed. Starting with model shapes, there were produced by solution spray-drying almost perfect cubes or parallelpipeds and, by suspension gas atomization, cylindrical particles of glass fibers. Dispersion of powders by air turbulence was treated theoretically and a computational investigation of the adhesional energy between two parallelpipeds at various mutual orientations begun. The size parameters of the produced particles were determined. A way of assessing the electric charge of a nonspherical particle is analyzed in view of the specificity of its motion and the relation to the principal translational resistances brought out. The effect of Brownian rotation on the translation of an aerosol particle was discussed. An apparatus for the determination of the principal resistances of a nonspherical particle at various Knudsen numbers has been constructed and a mathematical procedure for the elucidation of results developed.