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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Novel Treatments for Multi-phase Flow Prediction Inspired By Kinetic Theory

Ben Dhia, Zakaria January 2016 (has links)
This study entails an investigation of a novel moment closure, originally constructed for rarefied-gas prediction, to the modelling of inert, dilute, disperse, particle flows. Such flows are important in many engineering situations. As one example, in internal-combustion engines, fuel is often injected as a spray of tiny droplets and, during combustion, a cloud of tiny soot particles can be formed. These particle phases are often difficult to model, especially when particles display a range of velocities at each location in space. Lagrangian methods are often too costly and many Eulerian field-based methods suffer from model deficiencies and mathematical artifacts. Often, Eulerian formulations assume that all particles at a location and time have the same velocity. This assumption leads to nonphysical results, including an inability to predict particle paths crossing and a limited number of boundary conditions that can be applied. The typical multi-phase situation of many particles is, in many ways, similar to that of a gas compressed of a huge number of atoms or molecules. It is therefore expected that powerful techniques from the kinetic theory of gases could be applied. This work explores the advantages of using a modern fourteen-moment model, originally derived for rarefied gases, to predict multi-phase flows. Details regarding the derivation, the mathematical structure, and physical behaviour of the resulting model are explained. Finally, a numerical implementation is presented and results for several flow problems that are designed to demonstrate the fundamental behaviour of the models are presented. Comparisons are made with other classical models.
22

Fundamental concepts concerning the derivation of kinetic equations for mixtures

Thibault, Paul. January 1978 (has links)
No description available.
23

Stability of Granular Materials under Vertical Vibrations

Deng, Rensheng, Wang, Chi-Hwa 01 1900 (has links)
The influence of periodic vibrations on the granular flow of materials is of great interests to scientists and engineers due to both theoretical and practical reasons. In this paper, the stability of a vertically vibrated granular layer is examined by linear stability analysis. This includes two major steps, firstly, the base state at various values of mass holdup (Mt) and energy input (Qt) is calculated and secondly, small perturbations are introduced to verify the stability of the base state by solving the resultant eigenvalue problem derived from the linearized governing equations and corresponding boundary conditions. Results from the base state solution show that, for a given pair of Mt and Qt, solid fraction tends to increase at first along the layer height and then decrease after a certain vertical position while granular temperature decreases rapidly from the bottom plate to the top surface. This may be due to the existence of inelastic collisions between particles that dissipate the energy input from the bottom. It is also found that more energy input results in a lower solid fraction and a higher granular temperature. The stability diagram is constructed by checking the stability property at different points in the Mt-Qt plane. For a fixed Mt, the base state is stable at low energy inputs, and becomes unstable if Qt is larger than a critical value Qtc1. A higher value of Mt corresponds to a larger Qtc1. There also exists a critical mass holdup (Mtc), for Mt larger than Mtc, the patterns corresponding to the instabilities are standing waves (stationary mode); otherwise the flat layer appears (layer mode). Moreover, the stationary mode turns into the layer mode when Qt is increased beyond a critical value Qtc2. These findings agree with the experimental observations of other researchers (Hsiau and Pan, 1998). The effects of restitution coefficients (ep, ew) and material properties (dp, ρp) on the stability diagram are also investigated. Together with Mt and Qt these variables can be classified into two groups, i.e. the stabilizing factors (Mt, dp, ρp) and the destabilizing factors (Qt, ep, ew). The stability of the system is enhanced with increasing stabilizing factors and decreasing destabilizing factors. / Singapore-MIT Alliance (SMA)
24

Some problems on conservation laws and Vlasov-Poisson-Boltzmann equation /

Zhang, Mei. January 2009 (has links) (PDF)
Thesis (Ph.D.)--City University of Hong Kong, 2009. / "Submitted to Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves [90]-94)
25

BGK kinetic scheme for the shallow-water equations /

Que, Yin Tik. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 108-109). Also available in electronic version. Access restricted to campus users.
26

A study of the kinetics of oxidation of hydrogen bromide in the gaseous phase

Zahner, August William January 1932 (has links)
No description available.
27

The pyrolysis of ethyl chlorocarbonate

Lashbrook, Robert V., 1918- January 1941 (has links)
No description available.
28

The thermal decomposition of ethyl chlorocarbonate

Curry, Mary Jo, 1921- January 1942 (has links)
No description available.
29

Mobility measurements of ions in nitrogen and hydrogen with simultaneous mass identification of the ionic species

Barnes, William Spencer 05 1900 (has links)
No description available.
30

Low-field drift velocity measurements on mass-identified ions in nitrogen

Keller, George Emerson 05 1900 (has links)
No description available.

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