This study involved a geographic information systems (GIS) approach to modeling ground water pollution potential in the Southern Edwards Aquifer Region in Texas. The DRASTIC ground water model was analyzed using two methods. First, the effects of adding land cover data to the drastic model were evaluated. In the second approach, the effects of the removal of DRASTIC variables were evaluated. Six, five, and four variable models were generated and analyzed.

Water models are of great importance for different fields of studies such as fluid mechanics, nano materials, and biomolecule simulations. In this dissertation, we focus on the water models applied in atomistic simulations, including those of biomolecules such as proteins and DNA. Despite water's simple structure and countless studies carried out over the decades, the best water models are still far from perfect. Water models are normally divided into two types--explicit model and implicit model. Here my research is mainly focused on explicit models. In explicit water models, fixed charge n-point models are most widely used in atomistic simulations, but have known accuracy drawbacks. Increasing the number of point charges, as well as adding electronic polarizability, are two common strategies for accuracy improvements. Both strategies come at considerable computational cost, which weighs heavily against modest possible accuracy improvements in practical simulations. With a careful comparison between the two strategies, results show that adding polarizability is a more favorable path to take. Optimal point charge approximation (OPCA) method is then applied along with a novel global optimization process, leading to a new polarizable water model OPC3-pol that can reproduce bulk liquid properties of water accurately and run at a speed comparable to 3- and 4-point non-polarizable water models. For practical use, OPC3-pol works with existing non-polarizable AMBER force fields for simulations of globular protein or DNA. In addition, for intrinsically disordered protein simulations, OPC3-pol fixes the over-compactness problem of the previous generation non-polarizable water models. / Doctor of Philosophy / With the rapid advancements of computer technologies, computer simulation has become increasingly popular in biochemistry research fields. Simulations of microscopic substances that are vital for living creatures such as proteins and DNAs have brought us more and more insights into their structures and functions. Because of the fact that almost all the microscopic substances are immersed in water no matter they are in a human body, a plant, or in bacteria, accurately simulating water is crucial for the success of such simulations. My research is focused on developing accurate and fast water models that can be used by researchers in their biochemical simulations. One particular challenge is that water in nature is very flexible and properties of water can change drastically when its surroundings change. Many classical water models cannot correctly mimic this flexibility, and some more advanced water models that are able to mimic it can cost several times more computing resources. Our latest water model OPC3-pol, benefited from a new design, accurately mimics the flexibility and runs as fast as a traditional rigid water model.

The use of a swirling flow can provide a more uniform velocity distribution and a calmer filling condition according to previous studies of both ingot and continuous casting processes of steel. However, the existing swirling flow generation methods developed in last decades all have some limitations. Recently, a new swirling flow generator, the TurboSwirl device, was proposed. In this work, the convergent nozzle was studied with different angles. The maximum wall shear stress can be reduced by changing the convergent angle between 40º and 60º to obtain a higher swirl intensity. Also, a lower maximum axial velocity can be obtained with a smaller convergent angle. Furthermore, the maximum axial velocity and wall shear stress can also be affected by moving the location of the vertical runner. A water model experiment was carried out to verify the simulation results of the effect of the convergent angle on the swirling flow pattern. The shape of the air-core vortex in the water model experiment could only be accurately simulated by using the Reynolds Stress Model (RSM). The simulation results were also validated by the measured radial velocity in the vertical runner by the ultrasonic velocity profiler (UVP). The TurboSwirl was reversed and connected to a traditional SEN to generate the swirling flow. The periodic characteristic of the swirling flow and asymmetry flow pattern were observed in both the simulated and measured results. The detached eddy simulation (DES) turbulence model was used to catch the time-dependent flow pattern and the predicted results agree well with measured axial and tangential velocities. This new design of the SEN with the reverse TurboSwirl could provide an almost equivalent strength of the swirling flow generated by an electromagnetic swirling flow generator. It can also reduce the downward axial velocities in the center of the SEN outlet and obtain a calmer meniscus and internal flow in the mold. / Tidigare studier visar att ett roterande flöde kan ge en mer likformig hastighetsfördelning och en lugnare fyllning i både göt- och stränggjutning av stål. De befintliga metoderna för att generera ett roterande flöde har vissa begränsningar. En ny metod för att generera det roterande flödet, en så kallad TurboSwirl, föreslogs nyligen. I detta arbete undersöktes ett konvergent munstycke med olika vinklar för att se hur detta påverkade det roterande flödet som genererades i anordningen. Resultaten visar att skjuvspänningen i systemet kan reduceras genom att ändra munstyckets vinkel mellan 40º till 60º. En lägre maximal axiell hastighet kan också uppnås med en mindre konvergent vinkel på munstycket. Det är även möjligt att påverka den maximala axiella hastigheten och skjuvspänningen i systemet genom att förflytta den vertikala kanalen i anordningen. Vattenmodellexperiment har utförts för att validera simuleringsresultaten. Det kraftigt roterande flödet kunde endast beskrivas väl av Reynolds Stress Model (RSM). Validering utfördes också genom att mäta den radiella hastigheten i den vertikala kanalen med en Ultrasonic Velocity Profiler (UVP). TurboSwirl-anordningen vändes och kopplades till gjutröret för att generera det roterande flödet. Detta studerades både med numeriska modeller och med vattenmodellering. Ett periodiskt asymmetriskt roterande flöde observerades både i numeriska modellerna och i vattenmodellerna. För att modellera detta periodiska flöde så användes detached eddy simulation (DES) modellen. Resultaten då denna modell användes stämmer väl med de experimentella mätningarna. Denna nya design med TurboSwirl kan uppnå liknande styrka på det roterande flödet som när elektromagnetisk omrörning användes. Det resulterande roterande flödet leder till en lägre axiell hastighet i gjutröret samt en lugnare yta och ett lugnare flöde i kokillen. / <p>QC 20161123</p>

River dynamic behaviour is affected by variations both in the water phase and in the transported sediment phase. A change in the water regime may lead to significant morphological changes in the bed profile, which in turn may strongly influence the flow conditions. Transcritical flows over mobile beds are particularly challenging to model due to the rapid variation in space and time of the solid transport, and to the specific treatment required for boundary conditions. The one-dimensional numerical model presented in this dissertation divides the flow in two fully coupled layers: a water layer and a water-sediment transport layer. This model was initially designed to depict dam-break flows, which does not require a specific treatment of boundary conditions. An extension of the two-layer approach is proposed in order to properly take into account boundary conditions. The treatment of boundary conditions commonly relies on characteristics. Within a two-layer model, which embodies five governing equations, an appropriate eigenstructure analysis is developed based on numerical estimations. This novel approach results in a new characterization of the critical stage by defining a specific two-layer Froude number. The model is compared to the classical Saint-Venant – Exner approach and favourably applied to several typical situations: uniform flow, which allows a straightforward calibration of the model parameters; regressive erosion around a mild-to-steep slope transition; evolution of a mobile bed under a hydraulic jump; and scour hole formation downstream of a fixed bed.

Idag värms glasugnar upp med antingen gasol eller olja, detta projekt vill visa på möjligheten att istället använda gas från biobränsleförgasning som förbränns utan synliga flammor. Detta skulle miljömässigt ge fördelarna att biobränslen inte bidrar till växthuseffekten och ge förutsättningar för att minska kväveoxidutsläppen genom bättre teknik än dagens. För att visa att det är möjligt att både behålla produktionen och reducera kväveoxiderna med förgasningsgas konstruerades en modell av ugnen och strömningsbilden studerades i vattenmodell. För att undersöka värmeöverföringen i ugnen behöver en eller flera kalorimetrar konstrueras för att kunna användas vid varma försök. Dimensionsberäkningar gjordes som visade att detta är möjligt med vissa typer av kalorimetrar. / Today glassfurnaces are heated with LPG or oil, this project will show the possibility to use gas from biofuel gasification combusted without visible flames. This would give the environmental benefits that biofuels don´t contribute to the greenhouse effect and reduce nitrogenoxide emissions by better technique than today. To prove the possibility to retain todays production and reduce nitrogenoxide emissions a model of the furnace was constructed and the flow field was studied using water model technique. To examine the heat transfer in the furnace one or more calorimeters need to be constructed to be used in hot experiments. Dimensioning calculations were made that showed that this is possible provided certain specific designs.

The dynamics of the world's oceans occur at a vast range of length scales. Although there are theories that aid in understanding the dynamics at planetary scales and microscales, the motions in between are still not yet well understood. This work discusses a numerical model to study barotropic wind-driven gyre flow that is capable of resolving dynamics at the synoptic, O(1000 km), mesoscale, O(100 km) and submesoscales O(10 km). The Quasi-Geostrophic (QG) model has been used predominantly to study ocean circulations but it is limited as it can only describe motions at synoptic scales and mesoscales. The Rotating Shallow Water (SW) model that can describe dynamics at a wider range of horizontal length scales and can better describe motions at the submesoscales. Numerical methods that are capable of high-resolution simulations are discussed for both QG and SW models and the numerical results are compared. To achieve high accuracy and resolve an optimal range of length scales, spectral methods are applied to solve the governing equations and a third-order Adams-Bashforth method is used for the temporal discretization. Several simulations of both models are computed by varying the strength of dissipation. The simulations either tend to a laminar steady state, or a turbulent flow with dynamics occurring at a wide range of length and time scales. The laminar results show similar behaviours in both models, thus QG and SW tend to agree when describing slow, large-scale flows. The turbulent simulations begin to differ as QG breaks down when faster and smaller scale motions occur. Essential differences in the underlying assumptions between the QG and SW models are highlighted using the results from the numerical simulations.

<p>Idag värms glasugnar upp med antingen gasol eller olja, detta projekt vill visa på möjligheten att istället använda gas från biobränsleförgasning som förbränns utan synliga flammor. Detta skulle miljömässigt ge fördelarna att biobränslen inte bidrar till växthuseffekten och ge förutsättningar för att minska kväveoxidutsläppen genom bättre teknik än dagens.</p><p>För att visa att det är möjligt att både behålla produktionen och reducera kväveoxiderna med förgasningsgas konstruerades en modell av ugnen och strömningsbilden studerades i vattenmodell. För att undersöka värmeöverföringen i ugnen behöver en eller flera kalorimetrar konstrueras för att kunna användas vid varma försök. Dimensionsberäkningar gjordes som visade att detta är möjligt med vissa typer av kalorimetrar.</p> / <p>Today glassfurnaces are heated with LPG or oil, this project will show the possibility to use gas from biofuel gasification combusted without visible flames. This would give the environmental benefits that biofuels don´t contribute to the greenhouse effect and reduce nitrogenoxide emissions by better technique than today.</p><p>To prove the possibility to retain todays production and reduce nitrogenoxide emissions a model of the furnace was constructed and the flow field was studied using water model technique.</p><p>To examine the heat transfer in the furnace one or more calorimeters need to be constructed to be used in hot experiments. Dimensioning calculations were made that showed that this is possible provided certain specific designs.</p>

The dynamics of the world's oceans occur at a vast range of length scales. Although there are theories that aid in understanding the dynamics at planetary scales and microscales, the motions in between are still not yet well understood. This work discusses a numerical model to study barotropic wind-driven gyre flow that is capable of resolving dynamics at the synoptic, O(1000 km), mesoscale, O(100 km) and submesoscales O(10 km). The Quasi-Geostrophic (QG) model has been used predominantly to study ocean circulations but it is limited as it can only describe motions at synoptic scales and mesoscales. The Rotating Shallow Water (SW) model that can describe dynamics at a wider range of horizontal length scales and can better describe motions at the submesoscales. Numerical methods that are capable of high-resolution simulations are discussed for both QG and SW models and the numerical results are compared. To achieve high accuracy and resolve an optimal range of length scales, spectral methods are applied to solve the governing equations and a third-order Adams-Bashforth method is used for the temporal discretization. Several simulations of both models are computed by varying the strength of dissipation. The simulations either tend to a laminar steady state, or a turbulent flow with dynamics occurring at a wide range of length and time scales. The laminar results show similar behaviours in both models, thus QG and SW tend to agree when describing slow, large-scale flows. The turbulent simulations begin to differ as QG breaks down when faster and smaller scale motions occur. Essential differences in the underlying assumptions between the QG and SW models are highlighted using the results from the numerical simulations.

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Some passive houses are provided a warm supply flow inlet coming from a mechanical ventilation system, creating issues of shortcut ventilation as a result of an originated density layer stratification, since the supplied warm air is confined to the ceiling level. In this way, there exist several complaints of thermal discomfort and poor indoor environmental quality in passive houses. Thus, a method of periodic variation of the ventilation supply frequency is an option to increase mixing, aimed at de-stratifying the room conditions. A small-scale water model is employed in order to systematically explore the influence of the created standing waves from the supply input frequency and its interaction with stratification characteristics in the studied volume, hence operating with water as a working fluid and a paddle as an oscillating mechanical input. Measurements at three different input frequencies and at three input paddle locations have been performed, gathering vertical temperature gradients and visualization data from them. Thus, ventilation efficiency of passive houses is set to improve, consequently increasing their public acceptability, via reaching buoyancy resonance, i.e., matching the input frequency with the internal Brunt-Väisäla frequency of the fluid. Consequently, the shortcut ventilation issues may be mitigated and the public acceptability of passive houses increased, achieving a higher thermal comfort and economic and energy demand savings, while enhancing sustainable and renewable heating alternatives such as the heat recovery from the outgoing exhaust flow.