The objective of this study was to develop a 3-D model for The Pontchartrain Estuary that was capable of long-term mass conservative simulation of salinities. This was accomplished in a multi-stage approach involving: a physical model of salinity exchange through a pass; a 3-D FVCOM model of the physical experiment; the development and testing of an FVCOM model for an idealized Pontchartrain Basin; and for the entire estuary. The data from the physical model tests were used to validate the performance of the FVCOM model with density-driven flows. These results showed that hydrostatic FVCOM captured the primary internal wave movement. The idealized basin simulations were used to evaluate several issues related to salinity transport, namely the relative importance of baroclinic forcing, tidal forcing and hydrology. The idealized domain also permitted the testing of sigma-gradients, spatial distribution of friction coefficients, wind stress and various boundary treatments. The results showed that the density-driven exchange of saltwater at the open boundary required a baroclinic boundary condition for salinity as well as a lateral filter at the boundary on each sigma layer. A new radiative baroclinic open boundary condition was developed for FVCOM. When tides and hydrology were included, the FVCOM model was shown to reproduce the seasonal salinity that has been observed for long-term periods. It was also found that the simulation of tides and salinity in FVCOM is very sensitive to the spatial distribution of the friction coefficient; relatively low friction was required in the open water regions and high friction was needed in the passes and waterways to reproduce the tides and salinity distribution. A variable friction coefficient option was coded on FVCOM. The findings from the idealized model were utilized to setup two models for the actual estuary. Both models extend from Lake Maurepas, one to the Chandeleurs Islands and the other to Mobile Bay. The baroclinic open boundary and variable friction were implemented in these models. They were calibrated for tides and salinity. The 2008 Bonnet Carré Spillway Opening was applied to the first model. A tidal pumping effect in Lake Pontchartrain was observed and captured by the model.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Elevados nÃveis de pressÃo provocados pelo desligamento de bombas sÃo responsÃveis pelo elevado Ãndice de danos estruturais em adutoras. Um controle efetivo destas perdas requer um melhor dimensionamento do sistema ou dos dispositivos de atenuaÃÃo do golpe de arÃete. Esse ajuste depende das formulaÃÃes propostas para as equaÃÃes de continuidade e momento do golpe de arÃete. Neste sentido, a consideraÃÃo de modelos mais precisos tem se revelado Ãtil para o dimensionamento de sistemas hidrÃulicos. Muitas anÃlises tÃm sido feitas para transientes provocados por fechamento ou abertura de vÃlvulas, mas poucos avanÃos tÃm sido feitos na anÃlise de transientes provocados pelo desligamento de bombas. Assim, o principal objetivo deste trabalho à implementar um programa computacional que leve em consideraÃÃo formulaÃÃes de fator de atrito variÃvel e comportamento mecÃnico de condutos plÃsticos em transientes provocados por desligamento de bomba em adutoras. Resultados satisfatÃrios foram obtidos para um modelo hidrÃulico que considere o comportamento viscoelÃstico dos tubos. Os modelos de atrito variÃvel nÃo apresentaram resultados satisfatÃrios para esse tipo de evento transiente. / Elevated pressures caused by sudden and unexpected shutdown of pumps are usually responsible for structural damage in water pipes. An effective control of these losses requires an adequate designing of system or devices whose purpose is relieving the water hammer effects. This adjustment depends on the proposed formulations for the equations of continuity and momentum of the water hammer phenomenon. In this sense, the consideration of more accurate models has been useful for the designing of hydraulic systems. Many analyses have been made for transients caused by opening or closing of valves, but little progress has been made in the analysis of transients caused by sudden and unexpected shutdown of pumps. Thus, the main objective of this work is to implement a computational program that takes into consideration formulations of variable friction term and mechanical behavior of plastic pipes in transients caused by sudden pump shutdown in water pipe. Satisfactory results were obtained for a hydraulic model that considers the viscoelastic behavior of the pipes. The variable friction models showed no satisfactory results for this type of transient event.

Esta investigación consiste en dar a conocer los efectos de la variación de los parámetros de los materiales que existen en las presas debido al esfuerzo de confinamiento entre sus partículas que la componen. Para ello, en primer lugar, se describió la realidad problemática, los antecedentes y generalidades previos acerca del tema para determinar la presa a utilizar, que fue la de Palo Redondo, Chavimochic. En segundo lugar, en el marco teórico se expuso un conjunto de conceptos fundamentales necesarios para entender los tipos de presas que existen, los parámetros de resistencia de los materiales, análisis de estabilidad de taludes y el uso de herramientas computacionales como el SLIDE y el PLAXIS. En tercer lugar, se trabajó con dos métodos de trabajo (ángulo de fricción constante y ángulo de fricción variable), considerando la misma geometría y los valores del anteproyecto de la presa Palo Redondo y además, se usó un gráfico de relación de esfuerzo y ángulo de fricción considerando los materiales usados en la presa a estudiar, para calcular el factor de seguridad con el software SLIDE. Asimismo, para el uso del software PLAXIS se consideró subdivisiones en franjas de cada 10 metros respecto a la cara de la presa, para tratar de representar el proceso de construcción de la misma, ya que este programa trabaja con elementos finitos y así lograr calcular los esfuerzos y deformaciones de la presa. Finalmente, se realizó un análisis comparativo entre los resultados obtenidos de los dos métodos usados. / This research is about making known the effects of the variation of the parameters of the materials that exist in the dams due to the effort of confinement between their particles. To do this, in the first place, the problematic reality, the background and previous generalities about the subject to determine the dam to be used, which was that of Palo Redondo, Chavimochic, are described. Second, the theoretical framework presented a set of fundamental concepts necessary to understand the types of dams that exist, the parameters of resistance of materials, slope stability analysis and the use of computational tools such as SLIDE and PLAXIS. Third, select with two working methods (constant friction angle and variable friction angle), create the same geometry and the values ​​of the draft the Palo Redondo dam and use an abacus of the same document, to calculate the safety factor with the SLIDE software. Also, for the use of the PLAXIS software, subdivisions in strips of every 10 meters with the face of the dam are considered, to try to represent the construction process of the dam, since this program works with finite elements and the efforts are calculated and deformations of the dam. Finally, a comparative analysis was performed between the results obtained from the two methods used. / Tesis