No description available.

No description available.

No description available.

No description available.

A theoretical non-hydrostatic model is developed to describe the dynamics of a two-layer shallow water system in the presence of viscous and Coriolis effects. The Navier-Stokes equations are integrated over the water depth in each layer to obtain the layer-mean equations. To close the resulting equation set, perturbation expansions of the vertical momentum equation are used and the dynamic pressures are solved in terms of wave elevations and horizontal velocities. A preliminary analysis is also carried out and a result for the quasigeostrophic problems is given based on an previous study. Our final model is of the Bousinesq class which is nonlinear and dispersive, and includes the effects of surface wind stress, bottom friction, eddy diffusion and earth rotation. It is shown that our new model can be readily reduced to previous inviscid non-hydrostatic models. Our model can be used in numerical simulations to study real ocean problems such as hurricane generated waves, tidal induced current, and interactions among surface waves, internal waves and variable topographies. / Thesis (M. S.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 55-59). / UHM: Has both book and microform. / U.S. Geological Survey; project no. 06; grant agreement no. 14-08-0001-G2015

M.Ing. / In this study it is shown that numerical analysis, and more specifically computational fluid dynamics can be used to investigate, compare, predict and design lining/cooling system combinations for blast furnaces’ in order to ensure longer campaign life and better performance. Three currently available cooling systems namely, copper staves are investigated. These combined with four different refractory materials, namely high alumina, silicon carbide, semi-graphite and graphite, stated in order of increasing thermal conductivity.

D.Ing. / The aim of this thesis is to research the use of Computational Fluid Dynamics (CFD) as design tool to predict fluid flow across stationary and moving bluff bodies. The principle of moving meshes is introduced to move the body vertically with respect to time. The moving mesh idea is first tested on a square body with a coarse discretized flow domain for transient conditions. The results can be animated to see how the flow pattern and mesh change with time. The idea is then implemented on a cylinder with a very fine mesh to capture the build-up and dispersion of vortices being shed from the cylinder as it moves cyclically for transient conditions. With this first approach a bluff body is forced to move cyclically with respect to time in cross flow. Many possibilities now exist to apply this idea further for other applications where forced vibration is important.The next approach is to use CFD to simulate flow-induced vibrations of bluff bodies. The pressure force on the bluff body is considered as a first approach to solve this problem. The inertia mass of the body balancing the effect of the pressure force on the body is first used, but the results indicate that damping and stiffness also have to be considered to obtain more realistic results. The effect of the pressure force on the body shows generally a downwards movement of the body for the first period of simulation and in the case of the square, after six time steps of the period of simulation the .pressure force switches to a positive value with resulting upwards movement of the body. The effect of the total force (shear + pressure) on a bluff body is not presented in this thesis. CFD as design tool is researched for various bundle configurations of cylinders. A new concept of split cylinders is researched and the best configuration obtained for various horizontal and vertical spacings of downstream- and upstream cylinders and cylinder halves. Experimental results on cylinders in a - small scale wind tunnel are used to compare the numerical results with the obtained pressure distribution around a stationary cylinder and the concept of velocity distribution over and between a split cylinder. Further development of the numerical flow model is necessary to include elasticity and longer three dimensional spanwise lengths of the object to obtain predictions of real flow-induced vibrations of bluff bodies. This first approach of numerical predictions of flow across stationary and moving bluff bodies creates many possibilities of complementing experimental results and comparing the obtained results with each other.

No description available.

Call number: LD2668 .T4 1964 H99 / Master of Science

Suppose C(x,t) is the concentration at position x in Rᵈ and time t > 0 of a solute which is diffusing in some medium. If on a local scale the dispersion of the solute is governed by a constant dispersion matrix, 1/2(δ²), and a random velocity field, V(x), then C satisfies a convection-diffusion equation with random coefficients, (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) (1). Usually V(x) is taken to be μ + εU(x) where μ ε Rᵈ, U(x) is a given stationary random field with mean zero, and ε > 0 is a dimensionless parameter which measures the variability of V(x). Hydrological experiments suggest that on a regional scale the diffusion is classically Fickian with effective diffusion matrix D(ε) and drift velocity α(ε). Thus for large scales (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) (2) is satisfied by the solute concentration. Here τ and χ are respectively time and space measured on large scales. It is natural to investigate the relation of the large scale coefficients D and α to the statistical properties of V(x). To relate (1) to (2)--and thus to approximate D(ε) and α(ε)--it is necessary to rescale t and x and average over the distribution of V. It can then be shown that the transition form (1) to (2) is equivalent to (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) (3) where A = (∇•δ²∇)/2 + √nμ• ∇ and B(U) = √nU(√nx) • ∇. By expanding each side of (3) estimates of D(ε) and α(ε) can be obtained. The estimates have the form (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) (4). Both D₂ and α₂ depend on the power spectrum of U. Analysis shows that in at least the case of incompressible fluids D₂ is positive definite. In one dimensional transport α₂ < 0, hence α(k) < μ(k) through second order.