Validation of the CFD code NEPTUNE for a full scale simulator for decay heat removal systems with in-pool heat exchangers

In the present work, a multi physics simulation of an innovative safety system for light water nuclear reactor is performed, with the aim to increase the reliability of its main decay heat removal system. The system studied, denoted by the acronym PERSEO (in Pool Energy Removal System for Emergency Operation) is able to remove the decay power from the primary side of the light water nuclear reactor through a heat suppression pool. The experimental facility, located at SIET laboratories (PIACENZA), is an evolution of the Thermal Valve concept where the triggering valve is installed liquid side, on a line connecting two pools at the bottom. During the normal operation, the valve is closed, while in emergency conditions it opens, the heat exchanger is flooded with consequent heat transfer from the primary side to the pool side. In order to verify the correct system behavior during long term accidental transient, two main experimental PERSEO tests are analyzed. For this purpose, a coupling between the mono dimensional system code CATHARE, which reproduces the system scale behavior, with a three-dimensional CFD code NEPTUNE CFD, allowing a full investigation of the pools and the injector, is implemented. The coupling between the two codes is realized through the boundary conditions. In a first analysis, the facility is simulated by the system code CATHARE V2.5 to validate the results with the experimental data. The comparison of the numerical results obtained shows a different void distribution during the boiling conditions inside the heat suppression pool for the two cases of single nodalization and three volume nodalization scheme of the pool. Finaly, to improve the investigation capability of the void distribution inside the pool and the temperature stratification phenomena below the injector, a two and three dimensional CFD models with a simplified geometry of the system are adopted.

Studio della fluidodinamica e della reazione chimica in un reattore agitato tramite modellazione cfd

L’attività di tesi è stata rivolta a realizzare l’accoppiamento tra modelli di reazione chimica e modelli di fluidodinamica per una reazione eterogenea solido-liquido in un reattore agitato, in ambito di un codice commerciale di fluidodinamica numerica. Lo studio ha avuto come punto di partenza la definizione e la discretizzazione del dominio di calcolo tramite un apposito programma. Per una trattazione completa, si sono svolti studi preliminari volti ad identificare le incertezze dovute ai metodi numerici e i limiti dovuti alla formulazione dei modelli per la descrizione del sistema. Lo studio si è svolto considerando sistemi di complessità crescente, partendo da simulazioni monofase fino ad arrivare allo studio di diverse soluzioni per sistemi reagenti con reazioni eterogenee solido-liquido. Questi ultimi esempi applicativi sono serviti come verifica del modello sviluppato (dove con modello si è indicato l’insieme dei modelli relativi alla fluidodinamica accoppiati al modello di reazione). Questa attività ha contribuito ad affrontare un problema di simulazione completa e completamente predittiva dei reattori chimici, essendo la letteratura a riguardo limitata, a differenza di quella relativa alle simulazioni puramente fluidodinamiche.

Analisi cfd in un motore pfi del moto di tumble a carico parzializzato al variare dell'angolo di rotazione della valvola a farfalla

Studio del moto di tumble e della generazione di turbolenza tramite simulazioni CFD tridimensionali al variare del grado di parzializzazione e del verso di rotazione della valvola a farfalla

Effect of mesh distortion on the accuracy of high order vorticity-velocity CFD approaches

The numerical solution of the incompressible Navier-Stokes equations offers an alternative to experimental analysis of fluid-structure interaction (FSI). We would save a lot of time and effort and help cut back on costs, if we are able to accurately model systems by these numerical solutions. These advantages are even more obvious when considering huge structures like bridges, high rise buildings or even wind turbine blades with diameters as large as 200 meters. The modeling of such processes, however, involves complex multiphysics problems along with complex geometries. This thesis focuses on a novel vorticity-velocity formulation called the Kinematic Laplacian Equation (KLE) to solve the incompressible Navier-stokes equations for such FSI problems. This scheme allows for the implementation of robust adaptive ordinary differential equations (ODE) time integration schemes, allowing us to tackle each problem as a separate module. The current algortihm for the KLE uses an unstructured quadrilateral mesh, formed by dividing each triangle of an unstructured triangular mesh into three quadrilaterals for spatial discretization. This research deals with determining a suitable measure of mesh quality based on the physics of the problems being tackled. This is followed by exploring methods to improve the quality of quadrilateral elements obtained from the triangles and thereby improving the overall mesh quality. A series of numerical experiments were designed and conducted for this purpose and the results obtained were tested on different geometries with varying degrees of mesh density.

Effect of high order interpolation in the stability and efficiency of the time-integration process in vorticity-velocity CFD algorithms

The numerical solution of the incompressible Navier-Stokes Equations offers an effective alternative to the experimental analysis of Fluid-Structure interaction i.e. dynamical coupling between a fluid and a solid which otherwise is very complex, time consuming and very expensive. To have a method which can accurately model these types of mechanical systems by numerical solutions becomes a great option, since these advantages are even more obvious when considering huge structures like bridges, high rise buildings, or even wind turbine blades with diameters as large as 200 meters. The modeling of such processes, however, involves complex multiphysics problems along with complex geometries. This thesis focuses on a novel vorticity-velocity formulation called the KLE to solve the incompressible Navier-stokes equations for such FSI problems. This scheme allows for the implementation of robust adaptive ODE time integration schemes and thus allows us to tackle the various multiphysics problems as separate modules. The current algorithm for KLE employs a structured or unstructured mesh for spatial discretization and it allows the use of a self-adaptive or fixed time step ODE solver while dealing with unsteady problems. This research deals with the analysis of the effects of the Courant-Friedrichs-Lewy (CFL) condition for KLE when applied to unsteady Stoke’s problem. The objective is to conduct a numerical analysis for stability and, hence, for convergence. Our results confirmthat the time step ∆t is constrained by the CFL-like condition ∆t ≤ const. hα, where h denotes the variable that represents spatial discretization.

El artículo científico en inglés : aspectos teórico-descriptivos, pedagógicos y computacionales de una modelización sistémico-funcional

Este libro da cuenta de estudios realizados entre 1999 y 2008 en el marco del proyecto “RedACTe: Modelización contextual y lingüística del artículo de investigación, y desarrollo de un sistema de escritura asistida" (Fases I-V: UNCuyo y CONICET).

Conocimiento de la mecánica corporal

El personal de enfermería, es quien se ocupa de atender a los pacientes brindándoles ayuda, comodidad y apoyo. Muchas de las actividades cotidianas que realiza enfermería incluyen movimientos repetidos, traslado de pacientes, cambios de posturas y levantamiento de objetos pesados, lo que exige un considerable gasto de energía. El conocimiento y la adecuada aplicación de la mecánica corporal son un buen mantenimiento preventivo de la salud corporal, así mismo, contribuye a disminuir el riesgo de trastornos músculo-esqueléticas. Estos son un conjunto de lesiones inflamatorias y degenerativas de músculos, nervios, tendones y articulaciones. En el personal de enfermería son muy frecuentes, lo que repercute en la calidad de vida del individuo y provoca un descenso en la calidad asistencial. El objetivo principal de esta investigación es determinar la relación entre el conocimiento de la mecánica corporal y los trastornos músculo-esqueléticos, del personal de enfermería del Área de internación del Hospital Privado Quirúrgico de Mendoza, en septiembre de 2013.

Riesgos ergonómicos; conocimiento y aplicación de los principios de mecánica corporal en los servicios de maternidad y terapia intensiva

Debido al índice de enfermedades ocupacionales y accidentes de trabajos observados y registrados en el Hospital Enfermeros Argentinos de General Alvear, se puede inferir que el personal de enfermería posee escaso conocimiento teórico y práctico sobre los factores de riesgo que deben tenerse en cuenta al momento de prevenir accidentes laborales causados por las incorrectas posturas corporales y el uso inadecuado de la fuerza al trabajar con pacientes que necesitan ser trasladados de un lugar a otro. Es por ello que el personal de enfermería debe poseer una habilidad técnica que permita aplicarlo en el área que se representa, tanto como para el paciente, como para beneficio personal. Lo ideal es que se conozcan los factores de riesgo y que se puedan prevenir los accidentes de trabajo.

Motivación del personal de enfermería relacionado con la atención a pacientes con EPOC que requieren ventilación mecánica no invasiva

La presente investigación se realiza en el servicio de Terapia Intensiva del Hospital Luis C. Lagomaggiore e intenta demostrar la importancia de recuperar la motivación del personal de enfermería que trabaja con los pacientes con EPOC ventilados mediante VNI (ventilación no invasiva) aspecto que redunda directamente en la calidad de vida y atención de los pacientes. Los objetivos específicos de este estudio son: identificar los aspectos principales del rol de enfermería en la asistencia de los pacientes con EPOC; identificar los factores que influyen en la motivación del personal y relacionar los factores de motivación con el desempeño laboral.

De la naturaleza mecánica al organismo programado

Tanto las metáforas como los instrumentos informáticos de que se valen las nuevas "ciencias de la vida", cuyos logros son intensamente divulgados por los medios de comunicación, impregnan las formas de percibir, pensar y experimentar el mundo, y llegan a afectar la misma noción de qué significa ser humanos. Junto con los discursos y las soluciones técnicas que proponen la genética y las neurociencias emergen nuevas formas de concebir y tratar la materia orgánica, tanto humana como animal y vegetal. Así, mientras las herramientas mecánicas, estos nuevos relatos cosmológicos abandonan las viejas figuras retóricas de la mecanización para embarcar en un proyecto inédito: la "digitalización" de la vida. Se trata de un sueño inspirado en la compatibilidad entre los cuerpos y el nuevo instrumental técnico, cuya mayor ambición consiste en descifrar la información que define la esencia de cada organismo, con el fin de "reprogramar" sus códigos, circuitos y flujos vitales. Aunque suela presentarse como un proyecto meramente tecnológico y "naturalizado" en sus premisas y objetivos, vale la pena rescatar sus robustas raíces históricas y sus reverberaciones políticas, económicas y socioculturales.