Increasing municipal and regional water demands have reduced freshwater inflows to the Nueces Delta. These flow reductions impair the marsh ecosystem’s functionality. As part of a United States Army Corps of Engineers multi-agency collaboration to restore the Nueces River and its tributaries, we have developed a mass-conservative hydrodynamic model to analyze fate and transport of freshwater and tidal inflows to the Nueces Delta. The model is built upon the LIDAR bathymetric data collected by the Coastal Bend Bays and Estuaries Program (CBBEP). Input data includes tidal, salinity, and wind data obtained from the Texas Coastal Ocean Observation Network (TCOON), pumping data from the Nueces River Authority, precipitation data from NOAA, and river flow from the USGS. The underlying modeling method uses conservative finite-difference/volume discretization on a Cartesian rectangular grid to simulate the movement of water and salt fluxes across the delta. Sub-models to represent the hydraulic influence of flow constrictions (e.g. railroads trestles, culverts) have been developed. The model’s response to forcing from wind, precipitation, and roughness were analyzed. The time to spin up for the model was analyzed and found to be approximately seven days. Preliminary validation of the model was qualitative but the overall trend of the tide coming in appears correct at the monitoring stations analyzed, indicating that the lowest frequency forcing of the tide and wind are correct. The effects of pumping into the delta were investigated under different pumping conditions to reveal the area inundation and impacts on salinity from pumping. / text

In this paper, a global existence result of smooth solutions to the multidimen- sional nonisentropic hydrodynamic model for semiconductors is proved, under the assumption that the initial data is a perturbation of the stationary solutions for the thermal equilibrium state. The resulting evolutionary solutions converge to the stationary solutions in time asymptotically exponentially fast.

Abstract The main purpose of this study is to develop a hydrodynamic and water quality model using the system dynamic software-STELLA for the tidal river simulations. The model consists of three modules: the hydrodynamic module simulates the water level variation and the dynamic flow conditions in tidal rivers; the transport module simulates the temporal and spatial variations of dissolved matters; and water quality module simulates the bio-chemical reaction processes and the fates of the water quality variables. Water quality module was established from the conceptions of WASP6 with some modifications. Eight state variables are included in the water quality module, i.e. chlorophyll-a, organic phosphorus, inorganic phosphorus, organic nitrogen, ammonia, nitrate, carbonaceous biochemical oxygen demand, and dissolved oxygen. Most the hydrodynamic and water quality models, either imported or domestic developed, were coded in FORTRAN or other conventional programming languages. In this study, the system dynamics software STELLA has been used to construct the model. The study has overcome the difficulty of using STELLA to simulate space continuity and unsteady state condition of tidal river systems. By using STELLA, the environment model can easily be integrated with researches in social-economical studies. The theories and the developments of the model are described in the thesis, the calibration and verification processes of the model using observation data of the Tamshui River system are also describe in detail. The model can be used not only to simulate and to predict the tidal flow, salinity, temperature, and water quality conditions in the Tamshui River, but also be used to evaluate the effects of various water quality purification methods and strategies. Therefore, this model can also assist policymakers to make better decisions on the balancing the economic developments with environmental protections.

A new method is presented to provide automatic sequencing of multiple hydrodynamic models and automated analysis of model forecast uncertainty. A Hydrodynamic and oil spill model Python (HyosPy) wrapper was developed to run the hydrodynamic model, link with the oil spill, and visualize results. The HyosPy wrapper completes the following steps automatically: (1) downloads wind and tide data (nowcast, forecast and historical); (2) converts data to hydrodynamic model input; (3) initializes a sequence of hydrodynamic models starting at pre-defined intervals on a multi-processor workstation. Each model starts from the latest observed data, so that the multiple models provide a range of forecast hydrodynamics with different initial and boundary conditions reflecting different forecast horizons. As a simple testbed for integration strategies and visualization on Google Earth, a Runge-Kutta 4th order (RK4) particle transport tracer routine is developed for oil spill transport. The model forecast uncertainty is estimated by the difference between forecasts in the sequenced model runs and quantified by using statistics measurements. The HyosPy integrated system with wind and tide force is demonstrated by introducing an imaginary oil spill in Corpus Christi Bay. The results show that challenges in operational oil spill modeling can be met by leveraging existing models and web-visualization methods to provide tools for emergency managers. / text

The objective of this dissertation is the development of computer simulation-based models for the modeling of upper ionosphere, starting from the first principles. The models were validated by exact analytical benchmarks and are seen to be consistent with experimentally obtained results. This area of research has significant implications in the area of global communication. In addition, these models would lead to a better understanding of the physical processes taking place in the upper ionosphere.

No description available.

<p> The objective of this thesis was to undertake an uncertainty analysis on the outputs from a two-dimensional hydrodynamic model. The analysis utilized an application of the Resource Management Associates' RMA2 model for the Upper St. Lawrence River in Ontario, Canada. Two uncertainty analysis methods, First-Order Second Moment (FOSM) and Monte Carlo analysis, are applied to calculate the uncertainty in water levels and velocities computed by the model.</p> <p> Both uncertainty analysis methods can be applied together with two-dimensional hydrodynamic modelling, but based on the findings of this work, the FOSM method is preferred. First, FOSM estimates of uncertainty are slightly larger than those obtained using Monte Carlo analysis. Thus, FOSM provides a conservative estimate of the uncertainty, a positive characteristic. Second, the FOSM method is simpler to apply than Monte Carlo analysis, requiring less information to describe the model inputs, fewer model executions and computations to calculate the uncertainty. Third, FOSM provides an immediate indication of the primary contributors to the uncertainty in the output, where Monte Carlo analysis requires additional effort to do the same.</p> <p> The model input that contributed the most to the uncertainty in the model outputs is the bottom resistance represented in RMA2 using Manning's n. The uncertainty in Manning's n is large and the model is sensitive to the parameter. As a result, a significant amount of uncertainty in the model outputs is contributed by this parameter.</p> <p> Uncertainty analysis is a practical addition to the two-dimensional hydrodynamic modelling process. The effort required to complete an uncertainty analysis using the FOSM method is minimal and the resulting insight is meaningful. It provides information to the model developer, quantifying how good the model actually is. It also provides a measure of the accuracy of the model for future model users or clients using hydrodynamic modelling outputs.</p> / Thesis / Master of Applied Science (MASc)

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Tana River, the largest river in Kenya, is an important habit that supports numerous types of life, which creates an attractive environment. Occasionally loss of life and damage to property are experienced during floods. Upstream development of hydropower generation dams without consideration of downstream impacts is well documented in literature and the aftermaths are being well exhibited currently. The aim of the thesis is to investigate and identify factors that affect the flood levels in the Tana River Delta by using a two dimensional model and eventually drawing up a velocity- water depth interaction hazard classification map. Reviews of the literature clearly established that the floods in the delta are not generated by internal rainfall only but also operation of upstream dams accounting for 95% of the flood levels. Consequently, investigations of the impacts of dams have on flow regime were carried out. Probabilistic analysis revealed that post dam seasonal patterns has not been impacted but the magnitude of flood peaks has generally declined due to the attenuation of small peaks. However, large/flash floods (10 year Annual Recurrence Interval (ARI) spill at the dams causing major flooding downstream. Further probabilistic analysis on river discharges and sea water level was carried out to determine various ARI peaks. This incorporated climate change based on the 4th IPCC report. A two-dimensional hydrodynamic model was set up and calibrated with recorded discharges and theoretically derived parameters. Impacts of extreme tidal levels were investigated on the water levels and other factors limiting flood propagation. Finally, the model was used to simulate the 2, 50 and 100 year ARI inclusive of climate change floods and, based on Australian guidelines, flood lines and hazard maps were drawn. The results show that high tides elevate water levels in the delta in combination with the bottleneck effect at the rechanneled canal. The road crossing through the delta has inadequate bridges to convey the floods. The derived flood maps drawn (Figure 6-4) highlight that settlements in the lower delta are located within the 2 year ARI flood lines and that the extent of flooding is similar or less so in 50 and 100 year ARI flood peaks simulated. The model predicted the velocity and water depths with sufficient accuracy and recommendations are made that the study area should be extended upstream, and more field data should be collected to aid in calibration and that land use should be incorporated in flood map classification. In conclusion, the thesis has identified the flood hotspots and factors governing floods. These findings could assist in decision making by various agencies proposing flood mitigation or advocating post dam flooding scenarios. / AFRIKAANSE OPSOMMING: Die Tanarivier is die grootste rivier in Kenia en ’n belangrike habitat vir verskeie tipes diere en plante wat ‘n aantreklike omgewing skep.Verlies aan lewens en skade aan eiendom vind egter somtyds tydens oorstromings plaas. Die bou van damme vir die ontwikkeling van hidrokrag hoër op in die rivier sonder om die impak laer af in ag te neem, asook die gevolge daarvan, word dikwels in die lireratuur beskryf. Die doel met hierdie tesis is om die faktore wat die vloedhoogtes in die Tanarivier beïnvloed met die gebruik van ’n twee-dimensionele hidrodinamiese model te ondersoek en te identifiseer en om dan ’n gevaarsonekaart te teken wat die interaksie tussen waterspoed en -diepte toon. Die oorsig van die literatuur het getoon dat die oorstromings in die delta nie die gevolg is van reën in die binneland nie, maar dat die damme hoër op in die rivier verantwoordelik is vir 95% van die oorstromings. Dus is die impak van die damme op oorstromings ondersoek. Waarskynlikheidsontleding het oor die algemeen getoon dat die na-dam seisoenale vloeipatrone nie beinvloed is nie, maar dat veral die kleiner vloedpieke in die algemeen afgeneem het as gevolg van vloedattenuasie deur die damme. Groter en frats oorstromings (>1:10 ARI) veroorsaak egter steeds dat die damme oorloop en lei tot ernstige oorstromings. Die verdere waarskynlikheidsontleding van riviervloei en die seewatervlak is uitgevoer om die verskillende Jaarlikse Herhaling Periode (JHP) vlakke vas te stel. Dit het klimaatsverandering gegrond op die 4de IPCC verslag ingesluit. ʼn Twee dimensionele hidrodinamiese model is opgestel en gekalibreer teen waargenome vloei en teoreties-afgeleide parameters is gekalibreer. Die impak van uiterste getyvlakke asook faktore wat die oorstromings beperk is ondersoek. Die model is toe gebruik om die 2, 50 en 100 JHP vloedoorstromings te simuleer en vloedlyne en gevaarkaarte is volgens die Australiese riglyne geteken. Die resultate toon dat hooggety die watervlak in die delta laat styg veral in kombinasie met die bottelnek effek van die nuwe kanaal. Daar is te min brûe op die pad wat die delta deurkruis, om die vloede se vloei deur te laat Die kaarte wat geteken is toon dat daar nedersettings in die laer delta binne die 2 JHP jaar vloedarea is en dat die omvang van oorstromings dieselfde of laer is as die 50 en 100 JHP jaar vloedpieke wat gesimuleer is. Die model kan gebruik word om die vloeispoed en waterdieptes redelik akkuraat te voorspel en die volgende aanbevelings word gemaak. Toestande hoër op teen die rivier moet ondersoek word, meer data wat gedurende kalibrasie gebruik kan word moet versamel word en grondgebruik moet in die kaartklassifikasie ingesluit word. Ten slotte is die gevaarpunte vir oorstromings en die faktore wat oorstromings veroorsaak aangetoon. Hierdie bevindinge kan van nut wees as besluite geneem moet word veral wat betref die voorkoming van oorstromings nadat damme gebou is.

The discovery of carbon nanotubes by Iijima in 1991 has created a torrent of new research activities. Research on carbon nanotubes ranges from studying their fundamental properties, such as their electron band structure and plasma frequencies, to developing new applications, such as self-assembled nano-circuits and field emission displays. Robust models are now needed to enable a better understanding of the electronic response of carbon nanotubes. We use time-dependent density functional theory to derive a two-fluid two-dimensional (2D) hydrodynamic model describing the collective response of a multiwalled carbon nanotube with dielectric media embedded inside or surrounding the nanotube. We study plasmon hybridization of the nanotube system in the UV range, the stopping force for ion channelling, the dynamical image potential for fast ions, channelled diclusters and point dipoles, and the energy loss for ions with oblique trajectories. Comparisons are made of results obtained from the 2D hydrodynamic model with those obtained from an extension of the 3D Kitagawa model to cylindrical geometries.

L’objectif de cette thèse était la modélisation numérique de la torche à plasma à couplage inductive. (ICP). Nous avons établi les bases de données nécessaires : composition, propriétés thermodynamiques et de transport appliqués aux mélanges d’argon, d’acide nitrique et d’eau. Le modèle hydrodynamique de la torche ICP (7 spires) considère le plasma à l'équilibre thermodynamique et couple les équations de Navier-Stokes pour décrire l'écoulement du plasma aux équations de Maxwell pour décrire l'évolution du champ électrique et du champ magnétique. / The purpose of the work was the numerical modeling of the inductive coupling plasma torch. (ICP). We have established the necessary databases: composition, thermodynamic and transport properties applied to argon mixtures of nitric acid and water. The hydrodynamic model of the ICP torch (7 coils) considers the plasma at thermodynamic equilibrium and uses the Navier-Stokes equations to describe the plasma flow and the Maxwell equations to describe the evolution of the electric field and the magnetic field.