No description available.

No description available.

Abstract DEM (Distinct Element Method) models have found numerous applications in a number of engineering disciplines, such as material handling and transport, chemical, industrial, civil, mining and mineral processing. The thesis describes developments using PFC3D (Particle Flow Code in 3D) for simulating rock fragmentation by commercial explosives. Emphasis is on the realistic simulation of explosive detonation in the blasthole as well as the flow of explosive gas from the blasthole, through the fracture network and venting to the atmosphere. Detonation can be initialized at any point along discretized blastholes and proceed up or down the hole according to the Velocity of Detonation of the explosive. Each of the explosive properties (pressure, density, extent of reaction, energy and their time derivatives) is computed according to the conservation equations and the explosive equation of state at any point along the hole. At initiation, the product calculation begins at the sonic locus with input of the detonation product provided by the non-ideal detonation code Vixen-n. The Taylor wave is then computed as a function of the blasthole expansion, which depends on the rock mass response to loading. The explosive gas is treated as a non-steady, compressible fluid and can flow through an arbitrary and evolving fracture network developed in the rock mass as a function of explosive loading. The fracture network (and flow paths) is defined by the coalescence of discrete macro-cracks. The gas has the effect of draining the blasthole and loading the fracture surface by its pressure and drag forces. Fracture intersection with free-surfaces is monitored and venting to the atmosphere is allowed. Validation of the fluid flow scheme is performed by comparing numeric results to analytic solutions for flow in shock tubes. The complete model is demonstrated by simulating stress only models, gas flow models and complete models of field-scale blasts.

Thesis (M.S.)--Ohio University, November, 2001. / Title from PDF t.p.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1961. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 250-256).

Thesis (M.S.)--University of California, Berkeley, 1959. / "Chemistry-General" -t.p. Includes bibliographical references (p. 52-53).

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

No description available.

A fully elliptic computational method for the analysis of steady viscous flow in high speed subsonic centrifugal compressor impellers with tip leakage, is presented. A generalised curvilinear, non-orthogonal grid is utilised and the timeaveraged Navier-Stokes equations are transformed and expressed in a fully conservative form. The discretisation of the governing equations is performed through finite volume integration. The solution procedure employs a non-staggered variable arrangement and a SIMPLE based method for coupling the velocity and pressure fields. The turbulence effects are simulated with the use of the k-e model, modified to account for rotation and streamline curvature, and the near-wall viscous phenomena are modelled through the wall function method. The numerical model is implemented for the flow prediction in a series of two and three dimensional test cases. Incompressible flow predictions in twodimensional cascades and three-dimensional ducting systems with different geometrical features and inlet conditions are initially performed and the numerical results are compared against available experimental data. The final objective of the present study is achieved through the comparative study of the predictions obtained against the results of Eckardt's experimental investigation of the viscous compressible flow in a high speed radial impeller operating at design condition and in a backswept impeller at design and off-design conditions. In addition, the flow is simulated in the passages of the Rolls Royce GEM impeller which was tested at Cranfield at design and off-design flow rates. A jet/wake pattern was discerned in all the simulated centrifugal compressor cases and a good overall agreement was achieved with the measured wake formation and development; and, encouraging results were obtained on the evolution of the secondary flows. The tip leakage effects influenced the loss distribution, the size and the location of the wake flow pattern at the rotor exit. The effects of the flow mass rate on the detailed flow pattern and on the compressor performance have been well represented. In certain cases, the quality of the present predictions is an improvement over that obtained by other 'state-of-the-art' Navier-Stokes solvers. In conclusion, the developed finite volume flow model has captured a large number of complex flow phenomena encountered in the tested impellers and is expected to provide a useful aerodynamic analysis tool for stationary or rotating, axial or radial turbomachinery components.

Magister Scientiae - MSc / Computational Fluid Dynamics is the analysis of a system involving fluid flow, heat transfer and associated phenomena such as chemical reactions by means of a computer-based simulation. The simulations in this study are performed using (CFD) software package FLUENT. The mixture of two gases (Silane gas (SiH4) and Hydrogen gas (H2)) are delivered into the hot-wire chemical vapor deposition system (HWCVD) with the two deposited substrates (glass and Silicon). This process is performed by the solar cells group of the Physics department at the University of the Western Cape. In this thesis, the simulation is done using a CFD software package FLUENT, to model the gas-flow patterns inside the HWCVD system. This will show how the gas-flow patterns are affected by the varying temperature of the heater in each simulation performed in this study under a constant pressure of 60μBar of the system. / South Africa