Numerical modeling systems are very important tools to study tidal inlets. In order to test its capability and accuracy of solving multi-inlet system problems, this study selected two widely used numerical modeling systems: Coastal Modeling System (CMS) and Delft3D Modeling Package. The hydrodynamics modules of the two modeling systems were tested at John's Pass and Blind Pass, Florida, a dual-inlets system, based on a similar modeling scheme. Detailed bathymetric surveys and hydraulic measurements were conducted to collect water depths, tide conditions, wave and current velocities as the input data as well as verification data for the models. A comparison study was conducted by comparing computed hydrodynamic results from both models with the extensive field measurement data. Results show that both of the modeling systems yield better prediction for water levels than for current velocity. Furthermore, under the similar modeling scheme, Delft3D was able to capture the measured tidal phase lag between the ocean boundary and the coastal inlet, therefore gave better water level prediction than the CMS model. However, the CMS yielded current velocities that are closer to the measured values than the DELFT3D model. CMS has a more user-friendly Graphic User's Interface (GUI) for input data preprocessing and plotting and visualization of output data. Delft3D has faster calculation speed.

In some continental shelf sediments integrated benthic microalgal biomass is greater than the integrated phytoplankton biomass in the overlying water column. In addition, benthic microalgae may account for up to 10% of the primary production responsible for the coastal fishery yield of the eastern United States. A three-dimensional model of the eastern Gulf of Mexico examines the effects of water-column nutrient sources on the growth of benthic microalgae. To parameterize the exchange of nutrients across the sediment/water interface in these permeable sediments, a non-local exchange submodel was constructed and tested within the framework of the model's grid. Based on the results of the three dimensional simulations, the growth of benthic microalgae from water-column nutrients is highly dependent on the light limitation of overlying phytoplankton. When light is available to phytoplankton in high enough quantities, water-column nutrients are used up before reaching the sediments. When the overlying phytoplankton are light limited, nutrients are able to reach the sediments where the shade adapted benthic microalgae can grow.

Estimation of effective diffusion coefficients is essential to be able to describe the diffusive transport of solutes in porous media. It has been shown in theory that in the case of uncharged porous materials the effective diffusion coefficient of solutes is a function of the pore morphology of the material and can be described by their tortuosity (tensor). To estimate the apparent diffusion coefficients, the values of tortuosity and porosity should be known first. In contrast with calculation of porosity, which can be easily obtained, estimation of tortuosity is intricate, particularly with increasing micro-geometry complexity in porous media. Moreover, many engineering materials (e.g, clays and shales) are characterized by electrical surface charges on particles of the porous material which can strongly affect the diffusive transport properties of ions. For these materials, estimation of effective diffusion coefficients have been mostly based on phenomenological equations with no link to underlying microscale properties of these charged materials although a few recent studies have used alternative methods to obtain the diffusion parameters. / In the first part of this thesis a numerical method based on a recently proposed up-scaled Poisson-Nernst-Planck type of equation (PNP) and its microscale counterpart is employed to estimate the tortuosity and thus the effective and apparent diffusion coefficients in thin charged membranes. Beside this, a new mathematical approach for estimation of tortuosity is applied and validated. This mathematical approach is also derived while upscaling of micro-scale Poisson-Nernst-Planck system of equations using the volume averaging method. A variety of different pore 2D and 3D micro-geometries together with different electrochemical conditions are studied here. To validate the new approaches, the relation between porosity and tortuosity has been obtained using a multi-scale approach and compared with published results. These include comparison with the results from a recently developed numerical method that is based on macro and micro-scale PNP equations. / Results confirm that the tortuosity value is the same for porous media with electrically uncharged and charged particles but only when using a consistent set of PNP equations. The effects of charged particles are captured by the ratio of average concentration to effective intrinsic concentration in the macroscopic PNP equations. Using this ratio allows to consistently take into account electro-chemical interactions of ions and charges on particles and so excludes any ambiguity generally encountered in phenomenological equations. / Steady-state diffusion studies dominate this thesis; however, understanding of transient ion transport in porous media is also important. The last section of this thesis briefly introduces transient diffusion through bentonite. To do so, the micro Nernst-Planck equation with electro-neutrality condition (NPE) is solved for a porous medium which consists of compacted bentonite. This system has been studied before in another research using an experimental approach and the results are available for both transient and steady-state phases. Three different conditions are assumed for NPE governing equations and then the numerical results from these three conditions are compared to the experimental values and analytical phenomenological solution. The tortuosity is treated as a fitting parameter and the effective diffusion coefficient can be calculated based on these tortuosity values. The results show that including a sorption term in the NPE equations can render similar results as the experimental values in transient and steady state phases. Also, as a fitting parameter, the tortuosity values were found varying with background concentration. This highlights the need to monitor multiple diffusing ion fluxes and membrane potential to fully characterize electro-diffusive transport from fundamental principles (which have been investigated in first part of this thesis) rather than phenomenological equations for predictive studies. / This research has lead to two different journal articles submissions, one already accepted in Computers and Geotechnics (October 22, 2009, 5-yrs Impact Factor 0.884) and the other one still under review.

This thesis investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, under co-operation with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. To numerically represent WEC effects the influence of the WECs upon the wave field was parameterized using the power absorption data from the WECs. Because a large driver of the WECs influence on the wave field is absorbed wave power by the WEC, it is reasonable to attempt a parameterization based on this process. It was of interest as to whether this parameterization, which does not account for wave scattering among other physics, could provide a good estimate of far-field effects. Accurately predicting WEC-array effects in the far-field requires empirical validation. Previous WEC analysis and modeling studies had limited data available for model verification, and additionally had used idealized WEC performance. In the present work we develop a WEC-array parameterization for use in phase-averaged wave models (e.g. SWAN). This parametrization only considers the wave absorption effects of the WECs and the model predictions of far-field effects are compared to observations. Further testing of the SWAN model was performed against a phase-resolving model, WAMIT, to determine the significance of physics the WEC absorption parameterization does not capture, such as scattered waves. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field. / Graduation date: 2013

Cyclonic oceanic vortices (eddies) ranging from ~10 to 150km in diameter that travel along the Florida Keys are investigated. This study employs hydrodynamic parameters from simulations in a high-resolution (~900m horizontally), three-dimensional (26 vertical levels) HYbrid Coordinates Ocean Model regional application to study coastal to offshore interactions along the Florida Keys. These parameters are compared qualitatively to observations from Chlorophyll-a Satellite (SEAWiFs) and HF Radar (WERA). Further, eddy characteristics along the Florida Keys are determined using the Okubo-Weiss parameter combined with Sea-Surface Height fields for the period 2004- 2008. Additionally, their temporal scales are assessed using spectral time-series analysis via Welch?s Fast Fourier Transform and Wavelet Transforms. Some processes that influence eddy evolution along the Florida Keys are presented in the form of case studies. And finally, the relative contribution of mesoscale and submesoscale eddies to the upwelling along the Florida Keys is assessed, supporting the argument that these features contribute to produce water exchanges between the offshore flow and the coastal areas.

River plumes often develop in complex environments, where variable coastal and bottom topography, ambient currents, winds and tides may play important roles in shaping the plume evolution. When all these factors are present, the plume dynamics may become intricate and unclear. The objective of this study is to understand the processes controlling the dynamics of a large river plume that is affected by strong boundary currents, variable winds and complex topography. The Mississippi River (MR) plume is the study case of this dissertation work, and focus is given to the interactions between the plume and the offshore circulation of the Gulf of Mexico (GoM). A series of numerical experiments was designed to investigate the impact of different factors on the development of a large scale river plume in scenarios with variable degrees of complexity. First, a box-like model with an idealized estuary was designed to address the general development of a mid-latitude river plume and assess the variability of the plume with changes in the outflow conditions at the river mouth. The structure and development of the plume in the flat-bottom, receiving basin was highly dependent on the degree of freshwater mixing at the source. Larger freshwater mixing enhanced the estuarine gravitational circulation and modified the dynamical balance at the estuary mouth. Those changes effectively modified the shape of the bulge and length/transport scales of the coastal current. Sloping-bottom conditions further modified the development of the plume. Secondly, a Northern GoM model was designed and numerical experiments were conducted to investigate the specific dynamics of the MR plume, in the presence of both shelf and basin-wide circulation. In particular, buoyancy-driven (due to the MR and all other major Northern GoM rivers) and wind-driven currents were studied on the shelf, while the extension of the Loop Current and associated frontal eddies were considered as major factors in the shelf to offshore interactions; wind-driven, shelfbreak eddies were also considered. Process-oriented experiments demonstrate that westerly and southerly winds promoted the development of a surface Ekman layer that enhances the offshore advection of plume waters. The steep topography in the vicinity of the MR Delta was a favorable condition for that process. When the MR plume was subject to a full-blown scenario (realistically-forced experiment nested within a large-scale model), complex interactions between wind-driven and eddy-driven dynamics determined the fate of the plume waters. Offshore removal is a frequent plume pathway, and the offshore transport can be as large as the wind-driven shelf transport. The offshore pathways depend on the position of the eddies near the shelf edge, their life span and the formation of eddy pairs that generate coherent cross-shelf flows. Strong eddy-plume interactions were observed when the Loop Current (LC) system impinged against the shelfbreak, causing the formation of coherent, narrow low-salinity bands that extended toward the Gulf interior. The offshore transport of MR water is a year-round process, but the interactions between the MR plume and the LC system have large inter-annual variability. Plume to LC interactions are determined by episodic northward intrusions of the LC system in the NGoM. The interactions are dictated by the proximity of the LC system to the MR Delta and by wind effects. On average, plume to LC interactions correspond to ~ 12 % of the year-round, total freshwater transport near the MR Delta, but this percentage can go up to 30 % in individual years. At the time of the plume to LC interactions, an average value of LC freshwater entrainment was estimated to be ~ 4,150 m3 s-1. The findings presented here are a major contribution toward the understanding of the cross-marginal and basin-wide transport of MR waters by a large-scale current system, and the connectivity to remote regions, such as the South Florida region and the Florida Keys.

This thesis deals with the physical modeling of the initiation and propagation of upward positive leader discharges from grounded structures during lightning strikes. It includes the analysis of upward leaders initiated under the influence of the electric field produced by a dominant negative cloud charge and due to the combined action of a negative thundercloud and a descending downward stepped negative leader. Thus, a self-consistent model based on the physics of leader discharges is developed for the evaluation of the attachment of lightning flashes to any kind of grounded structure. The predictions of the model have been found to be in good agreement with the results of laboratory long air gap experiments and with classical and altitude rocket triggered lightning experiments. Due to the high application level and predictive power of the developed model, several contributions to the physical understanding of factors influencing the initiation and propagation of upward positive leaders during thunderstorms have been made. For instance, it has been found that the initiation of upward connecting leaders is strongly affected by the average velocity of the downward stepped leader. Similarly, it is shown that the switching voltage impulses used in the laboratory do not “fairly approximate” the electric fields produced by a descending downward leader, as claimed by supporters of Early Streamer Emission (ESE) devices. Furthermore, it is found that the space charge layer created by corona at ground level significantly increases the thundercloud electric fields required to initiate upward lightning leaders from tall objects. On the other hand, it is also shown that the upward leader velocity depends on the downward leader average velocity, the prospective return stroke current, the lateral distance of the downward leader channel and the ambient electric field. By implementing the model to the analysis of complex structures, it has been observed that the corners of actual buildings struck by lightning coincide rather well with the places characterized by low leader inception electric fields. Besides, it has been found that the leader inception zones of the corners of complex structures do not define symmetrical and circular regions as it is generally assumed.

The Brunswick No. 6 area, which is located in the Bathurst Mining Camp, New Brunswick, Canada, is the focus of this thesis. Almost a decade ago, in order to improve the understanding of the crustal structures and explore for new mineral deposits at depth, three 2D seismic profiles totaling about 30 km and 3D seismic data covering an area of about 38 km2 were acquired from the study area. Petrophysical properties including compressional-wave velocity and density were also measured in two deep boreholes in the area. These data were recovered and reanalyzed, and the improved seismic images interpreted as the main part of this PhD thesis. A prestack DMO and poststack migration algorithm was considered for processing both 2D and 3D data. Processing of 2D data revealed shallow and deep reflections, which correlate well with surface geology. Steeply-dipping reflections, some of which could host mineral deposits, were imaged down to a depth of 6-7 km. Processing of 3D data showed similar results to the processed 2D profiles. Nevertheless, the non-orthogonal nature of the 3D survey, combined with irregular distribution of offsets, azimuths and trace midpoints, caused a severe acquisition footprint masking reflections in the DMO-corrected unmigrated stacked cube. An FK-dip filter in the wavenumber domain was designed to reduce the effects of the acquisition footprint. To better understand wave propagation and scattering effects, calculated acoustic impedance log from the available borehole data was used to estimate vertical scale length using a von Karman autocorrelation function. 2D synthetic models representative of heterogeneity in the area were generated accounting for the estimated scale length. Numerical modeling was used to study the scattering effects on the synthetic models, where some predefined targets were superimposed in the provided 2D heterogeneous medium. The effects of variable source frequency, longer horizontal scale length and petrophysical fluctuations of heterogeneous medium were also investigated. The modeling results indicate that, in the presence of large horizontal, but small vertical scale lengths (structural anisotropy), the identification of mineral deposits is possible in the unmigrated stacked sections, but can be challenging in the migrated sections.

The general objective of the research effort reported in this thesis was to develop the knowledge required to optimize the design and operation of solid and semi-solid manure handling and land application equipment. Selected physical and rheological properties of manure products deemed to have an influence on the performances of manure handling and land application equipment were measured and general trends were identified among the measured properties. Relationships were also established between the measured properties and the type of manure as well as its total solids concentration. Field experiments were carried out to evaluate the effects of selected mechanical configurations, operating parameters and product properties on the discharge of manure spreaders. The influence of the type of conveying system (scraper conveyor and system of four augers) and the velocity at which it is operated, the geometry of the holding system and the position of a flow-control gate were all included in the analysis. The discharge rates of the machines as well as the specific energy required by the unloading operations were measured. A numerical modeling method called discrete element method (DEM) was used to create virtual manure, a numerical model of the real product. The measured physical and flow properties were used to develop and validate the virtual manure models. It was found that manure products could successfully be represented in a DE framework and that several parameters defining the contact constitutive model in the DEM had an influence on the behaviour of the virtual products. The DEM was then used to study machine-product interactions taking place in handling and land application equipment. Results from field experiments carried out using various land application equipment were used in the development and validation of the interaction models. The predicted flow rates and power requirements were in good agreement with measured data. The results obtained allowed for a better understanding of the flow of manure products in manure handling and land application equipment. It was found that the constitutive model used for the product influenced the results of the machine-product interactions models. A precision banded applicator under development at the University of Saskatchewan was also modeled. The discharge rate of this equipment is influenced by a number of parameters. The predicted mass distribution across the width of the banded applicator was well correlated to the experimental results. The models developed in this thesis have the potential to become powerful engineering tools for the design of improved machines for the handling and land application of solid and semi-solid manure.

In this thesis, studies associated with the stability analyses of the box-shaped dump-site culvert constructed in Tinaz Surface Mine of Turkish Coal Enterprises (TKi) are presented. In addition, stability conditions of other culvert alternatives are evaluated. Existence of creeks in a surface mining area is a significant factor to be considered in selection of dump-site location. Since, the dumped overburden material on the valley acts as a barrier and behaves like a dam causing flood problem behind the dump-site. TKi engineers prevented the flood potential that might have occurred behind the dump-site by constructing a 480-meter long reinforced-concrete culvert on the downstream of Gevenez Creek Valley. However, considerable amount of deformations occurred in the first 100 meters of the culvert, as a result of overburden material being replaced on this structure. In order to determine the failure mechanism associated with the culvert, a series of numerical modeling analyses were carried out utilizing back analysis technique. The validity of the numerical model was justified by convergence measurements and observations carried out inside the culvert as overburden material being replaced on the stable part of this structure. Finally, based on the numerical model developed, the stability of other culvert alternatives that could be used in future projects were evaluated considering different embankment conditions (positive projecting and negative projecting), bedding conditions (impermissible, ordinary, first-class and concrete cradle), culvert shapes (box and circular) and dumping conditions.