Clustering and collision of inertial particles in random velocity fields

The influence of clustering on the collision rate of inertial particles in a smooth random velocity field, mimicking the smaller scales of a turbulent flow, is analyzed. For small values of the the ratio between the relaxation time of the particle velocity and the characteristic time of the field, the effect of clusters is to make more energetic collisions less likely. The result is independent of the flow dimensionality and is due only to the origin of collisions in the process of caustic formation.Comment: 4 pages, 3 figures, revtex

Particle dispersion models and drag coefficients for particles in turbulent flows

Some of the concepts underlying particle dispersion due to turbulence are reviewed. The traditional approaches to particle dispersion in homogeneous, stationary turbulent fields are addressed, and recent work on particle dispersion in large scale turbulent structures is reviewed. The state of knowledge of particle drag coefficients in turbulent gas-particle flows is also reviewed

Clustering and collisions of heavy particles in random smooth flows

Finite-size impurities suspended in incompressible flows distribute inhomogeneously, leading to a drastic enhancement of collisions. A description of the dynamics in the full position-velocity phase space is essential to understand the underlying mechanisms, especially for polydisperse suspensions. These issues are here studied for particles much heavier than the fluid by means of a Lagrangian approach. It is shown that inertia enhances collision rates through two effects: correlation among particle positions induced by the carrier flow and uncorrelation between velocities due to their finite size. A phenomenological model yields an estimate of collision rates for particle pairs with different sizes. This approach is supported by numerical simulations in random flows.Comment: 12 pages, 9 Figures (revTeX 4) final published versio

Postcard: Souvenir National Encampment G.A.R, Kansas City, 1916

This color printed postcard features an illustration of an American flag on the left side of the card. There is blue and red text printed at the top. There is handwriting on the front and back of the card.https://scholars.fhsu.edu/tj_postcards/1533/thumbnail.jp

Business Sustainability: An Analysis of Three Enterprises in Charlotte, North Carolina

Sustainability is defined in varying ways by businesses for reasons such as industry, stakeholder expectations, compliance, and other factors. In this case study, three companies, Domtar, Duke Energy, and Nucor, are examined on their approach to reporting and practicing environmental, social, and economic sustainability. Content analysis was used to identify themes in corporate paid, owned, and earned media. Interviews with facility managers were used to understand how management implements sustainable practices on a facility level. This case study examines in detail how these companies use different language, tools, and systems to progress sustainable development in a globalized economy. Results showed that in earned media, companies were socially and economically analyzed and not environmentally, unless responding to a crisis. In owned media, companies organized their sustainability priorities in a way they believed most represented their company. In sustainability reports, the more complicated the business portfolio, the more complicated it becomes to differentiate data sets. On all three reports, the most under-reported pillar of sustainability was environmental. All three companies have a huge ecological footprint and very general data regarding it is reported

How Do Family Background and Self-Esteem Affect an Individual’s Perception of Gender-Role Portrayal in Online Advertisements?

The purpose of this study is to further understand the relationship of family background and how it affects self-esteem and the perception of gender roles in online imagery. This study focuses on how our history serves as a lens to see gender roles. The schema theory, created by Robert Axelrod, is a model suggesting that people have a “pre-existing assumption about the way the world is organized” (Axelford, 1974). Furthering this theory is Bem\u27s (1981) Gender Schema Theory, which proposes that one\u27s sexual self-concept affects how one structures items in memory. These theories, applied to the understood roles and activities that we see our parents perform, should relate to how we see people in the media take on certain roles and activities in online advertisements. The method for collecting data is a survey broken down into questions of demographics, family history, self-esteem, and ten randomized advertisements portraying traditional, decorative, and non-traditional gender roles for both men and women. If we can begin to understand the relationship between family background and advertisement effectiveness, then advertisers can see the real cultural values and changing gender-role identities in consumers

An Audible Demonstration Of The Speed Of Sound In Bubbly Liquids

The speed of sound in a bubbly liquid is strongly dependent upon the volume fraction of the gas phase, the bubble size distribution, and the frequency of the acoustic excitation. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. This effect can be audibly demonstrated using a one-dimensional acoustic waveguide, in which the flow rate of air bubbles injected into a water-filled tube is varied by the user. The normal modes of the waveguide are excited by the sound of the bubbles being injected into the tube. As the flow rate is varied, the speed of sound varies as well, and hence, the resonance frequencies shift. This can be clearly heard through the use of an amplified hydrophone and the user can create aesthetically pleasing and even musical sounds. In addition, the apparatus can be used to verify a simple mathematical model known as Wood's equation that relates the speed of sound of a bubbly liquid to its void fraction. (c) 2008 American Association of Physics Teachers.Mechanical Engineerin

Measurement of Both Gas and Particle Velocity in Turbulent Two-Phase Flow

A laser-Doppler anemometer was used to measure the velocity of both the gas and particles in a turbulent two-phase flow for conditions when the distribution of the velocities of the two phases overlaps. The velocities from the two phases are separated by comparing the Doppler amplitude to the pedestal amplitude. Results of the measure of the gas-particle flow downstream of a nozzle mounted in a circular pipe are presented