A two-dimensional model was developed to predict concentration profiles from passive, laminar mixing of concentration layers formed in a fractal-like merging channel network. Both flat and parabolic velocity profiles were used in the model. A physical experiment was used to confirm the results of the model. Concentration profiles were acquired in the channels using laser induced fluorescence. The degree of mixing was defined and used to quantify the mixing in the test section. Although the results of the experiment follow the trend predicted by the two-dimensional model, the model under predicts the results of the experiment. A three-dimensional CFD model of the flow field in the channel network was used to explain the discrepancies between the two-dimensional model and the experiment. For the channel network considered, the degree of mixing is a function of Peclet number. The effect of geometry on the degree of mixing is investigated using the two-dimensional model by varying the flow length, the width of the inlet channels, and the number of branching levels. A non-dimensional parameter is defined and used to predict an optimum number of branching levels to maximize mixing for a fixed inlet channel width, total length, and channel depth. / Graduation date: 2003

There are numerous techniques for improving the mixing of fuel and oxidant species. However, many of these methods cannot be applied to combustion systems due to material limitations. A means of mixing the reacting species without physically invading the flow stream is therefore desired. In this work, induced electromagnetic forces known as Lorentz forces are considered as a means of enhancing the combustion of co-flowing reactant streams. To evaluate the effect of various parameters on the mixing process, a non-dimensional description is derived and used to develop a numerical model. Numerical experiments are performed based on a three level Box-Behnken design in which the dimensionless Lorentz force parameter, Reynolds number, and Euler number are varied. The Lorentz force parameter has a large effect on the mixing process. The Reynolds number has a minor effect on mixing, and the Euler number has a negligible effect. Confirmation of these results through experimental work is needed. Approaches that could be used to verify these results experimentally are outlined, and the construction and testing of a burner suitable for further experiments on Lorentz mixing is described. / Graduation date: 1997

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on Nov. 29, 2006). Includes bibliographical references (p. 202-203).

In previous studies the slotted orifice plate has demonstrated superior performance characteristics to those of the standard orifice plate. In this study, these comparisons are investigated further. The response characteristics of the slotted orifice plate to the standard orifice plate and V-Cone for two-phase flows of water and air at various qualities, flow rates, and pressures are shown visually. The effect of oil as it flows through a slotted orifice plate and standard orifice plate are visually documented. The effect of manufacturing accuracy on the slotted orifice plates is investigated as to the effect on the coefficient of discharge, percent change in pressure, and Reynolds number. The slotted orifice plate mixes two-phase flow better than the standard orifice plate and V-Cone. There is a manufacturing effect on the slotted orifice plates; the larger the area of the slots, the larger the discharge coefficient.

This dissertation investigates the dynamics of the tidally modulated outflow from the Columbia River mouth using high resolution measurements of velocity, density and turbulent microstructure. At high tide, flow through the river mouth reverses from flood (onshore) to ebb (offshore). During ebb, buoyant fluid issues from the river mouth and spreads offshore across the ocean surface. This is the Columbia River tidal plume. The fluid velocity of the tidal plume is super-critical (greater than the wavespeed of coastal stratification), which creates a zone of sharp surface velocity convergence at its leading edge, causing a front to form. From early ebb to peak ebb, constant front propagation speed and plume expansion rate are controlled by a linearly increasing volume-flux through the river mouth. Within the plume, turbulence at the plume base is strongly related to the difference between the shear-squared, S², and four times the buoyancy frequency squared, 4N². A parameterization based on the excess shear-squared, S² - 4N², represents Reynolds stress well, indicating that it is driven by Kelvin-Helmholtz instability. During peak ebb of large tides, high volume-flux through the mouth drives high S² - 4N², causing high plume-base stress, which forces significant deceleration of the plume. During smaller tides the volume-flux is smaller, S² - 4N² lower, and the stress too weak to significantly decelerate the plume. During mid-ebb of both small and large ebbs, increasing buoyancy flux from the river mouth raises plume stratification, which suppresses S² - 4N² and stress. As ebb ends, decreasing volume flux and deflection by the Coriolis effect limit plume expansion. This weakens surface velocity convergence, causing the front to diffuse. On longer timescales, plume N² is modulated by changes in river flow; higher river flow causes higher N². During peak ebb of large tides this increase in N² supports higher S², resulting in higher S² - 4N², which causes larger internal stress. These results describe the primary dynamics of the Columbia River tidal plume from front formation to late-ebb, and relate variability in those dynamics to tidal and river-flow forcing. / Graduation date: 2011 / Access restricted to the OSU Community at author's request from Jan. 26, 2011 - Jan. 26, 2013

Application of zinc oxide (ZnO) nanoparticles was evaluated as a possible measure to mitigate the levels of hydrogen sulphide (H2S), ammonia (NH3) and odour in swine facilities. Two deployment techniques were investigated: direct mixing of zinc oxide nanoparticles into the slurry, and filtration with nanoparticles as filtering media for the manure gases. The overall goal of this work was to determine the impact of the treatments on hydrogen sulphide, ammonia and odour emissions, pig performance and manure characteristics as well as to assess the feasibility of the application of this technology in a typical swine barn. Semi-pilot scale tests were conducted to evaluate operational factors in open system conditions, the results of which showed that the mixing method required a particle-to-slurry ratio of 3 grams of zinc oxide per litre of slurry to control hydrogen sulphide and ammonia levels. Using the air filtration technique, a fluidized bed filter design with a 0.28 g/cm2 loading rate and rated at 0.5 m/s face velocity was found to be the most effective combination for controlling gas levels. Room-scale experiments were conducted in specially designed chambers to assess the effectiveness of the treatments under conditions that represent commercial swine production. The addition of zinc oxide nanoparticles into the manure achieved more than 95% reduction in hydrogen sulphide levels while no significant effects on ammonia concentrations were observed. Zinc oxide nanoparticles were persistent in maintaining low hydrogen sulphide levels up to 15 days after treatment application. On the other hand, the ventilation air recirculation system with a zinc oxide filter achieved significant reduction in both hydrogen sulphide and ammonia concentrations at the animal- and human-occupied zones. Neither treatment had any significant impact on pig performance and manure nutrient characteristics. Estimates of the cost of application of the treatments in a 100-head grow-finish room showed that employing the air filtration method amounted to around 3.8% of the average total cost of production, which was economically more feasible than the mixing method; however, various options can be pursued to further reduce the cost of application of both treatments.

Application of zinc oxide (ZnO) nanoparticles was evaluated as a possible measure to mitigate the levels of hydrogen sulphide (H2S), ammonia (NH3) and odour in swine facilities. Two deployment techniques were investigated: direct mixing of zinc oxide nanoparticles into the slurry, and filtration with nanoparticles as filtering media for the manure gases. The overall goal of this work was to determine the impact of the treatments on hydrogen sulphide, ammonia and odour emissions, pig performance and manure characteristics as well as to assess the feasibility of the application of this technology in a typical swine barn. Semi-pilot scale tests were conducted to evaluate operational factors in open system conditions, the results of which showed that the mixing method required a particle-to-slurry ratio of 3 grams of zinc oxide per litre of slurry to control hydrogen sulphide and ammonia levels. Using the air filtration technique, a fluidized bed filter design with a 0.28 g/cm2 loading rate and rated at 0.5 m/s face velocity was found to be the most effective combination for controlling gas levels. Room-scale experiments were conducted in specially designed chambers to assess the effectiveness of the treatments under conditions that represent commercial swine production. The addition of zinc oxide nanoparticles into the manure achieved more than 95% reduction in hydrogen sulphide levels while no significant effects on ammonia concentrations were observed. Zinc oxide nanoparticles were persistent in maintaining low hydrogen sulphide levels up to 15 days after treatment application. On the other hand, the ventilation air recirculation system with a zinc oxide filter achieved significant reduction in both hydrogen sulphide and ammonia concentrations at the animal- and human-occupied zones. Neither treatment had any significant impact on pig performance and manure nutrient characteristics. Estimates of the cost of application of the treatments in a 100-head grow-finish room showed that employing the air filtration method amounted to around 3.8% of the average total cost of production, which was economically more feasible than the mixing method; however, various options can be pursued to further reduce the cost of application of both treatments.

Cutter Soil Mixing (CSM) is a recently developed deep mixing technique that has grown to include the treatment of sandy and silty soils. This study seeks to investigate the influence of (i) sand-silt ratio, (ii) cement content, (iii) water content and (iv) time on the unconfined compressive strength of saturated cement-treated soil specimens. A new test device and method of specimen reconstitution were conceived in order to obtain a saturated mix of soil and cement. A comparison of results show strength increases non-linearly to decreasing total water-cement ratio, and that this trend is largely independent of sand-silt ratio. Furthermore, strength increases non-linearly with time and is independent of sand-silt ratio. Lastly, it is recommended that the strength be correlated with total water-cement ratio rather than cement content, in order to improve data reporting and provide design guidance to engineering practice.

Abstract Internal waves have been identified as one of the most active mechanisms producing vertical mixing in continental slope and shelf waters. The major contribution of mixing are due to internal tides, however, shorter period internal waves are unlikely to be the main source of energy for mixing, especially on the inner part of the continental shelf. In this study, we observe the vertical mixing of huge internal waves in the Dongsha Atoll South China Sea. These solitary waves were originate near the Luzon Strait, propagated westward across the basin, evolving into internal solitary wave trains and dissipated at the western shallow continental shelf. The wave energy and phase speed reduced significantly during the shoaling process. Internal waves and their likely related induced mixing phenomena are analyzed based on multiple cruises of observations consisted of CTD hydrographic measurements, water samples and moored thermister strings. Data analyses show that the mixing processes are related to depths of water and the interfacial of wave. For depression wave in the deep water zone, upper layer water may push downward producing vertical mixing beyond the thermocline. The mixing usually dilutes the nutrients in the upper layer of water column. Statistics suggest that the N:P ratio is 12:1 which is lower than the standard value (16:1) indicating the region is nitrogen deficit, similar to most of the surface water in South China Sea. The depression solitons in deep water may evolved to a packet of elevation waves in the shallow water area at ¡§turning point¡¨ of approximately equal depth of upper and lower layers. The mixing of shallow water internal waves can entrain cold nutrient rich water from the lower layer into the frequently nutrient depleted subsurface layer to enhance the local coral reef ecosystem. For example, CTD profiles (2008.5.7) before and after the passage of internal wave show large differences. The vertical density distribution has dramatic change. The column was stratified in two layers in normal condition. The internal waves perturbed the water column into stepwise multi-layer density distribution. The water at 50 m showed temperature decrease by 6 ¢J, salinity increase by 23 psu, density increase by 1.8 , fluorescence decrease by 0.065 £gg/L etc. The MODIS chlorophyll images confirm the high concentration fertilized by the internal wave pumping near the NE region of the Dongsha Atoll.

The effect of finite Reynolds numbers on chaotic advection is investigated for two dimensional lid-driven cavity flows that exhibit topological chaos in the creeping flow regime. The emphasis in this endeavor is to study how the inertial effects present due to small, but non-zero, Reynolds number influence the efficacy of mixing. A spectral method code based on the Fourier-Chebyshev method for two-dimensional flows is developed to solve the Navier-Stokes and species transport equations. The high sensitivity to initial conditions and the exponentional growth of errors in chaotic flows necessitate an accurate solution of the flow variables, which is provided by the exponentially convergent spectral methods. Using the spectral coefficients of the basis functions as solved through the conservation equations, exponentially accurate values of velocity everywhere in the flow domain are obtained as required for the Lagrangian particle tracking. Techniques such as Poincare maps, the stirring index based on the box counting method, and the tracking of passive scalars in the flow are used to analyze the topological chaos and quantify the mixing efficiency.