Thesis DESARROLLO DE UN CÓDIGO PARA LA MODELACIÓN DE SUSPENSIONES SÓLIDAS USANDO EL MÉTODO DE LA FRONTERA INMERSA
Date
2018
Authors
PEREZ FUENTES, AGUSTIN IGNACIO
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Abstract
Se realiza una investigación respecto a los métodos numéricos que se aplican actualmente para el estudio de flujos particulados con un enfoque dirigido hacia la presencia de grandes cantidades de sólidos en suspensión.Dentro de las metodologías encontradas, se opta aquella propuesta por Uhlmann(2005) que consiste en una formulación de las ecuaciones de Navier-Stokes con un término adicional que contiene los efectos de los cuerpos sumergidos.Esta tipo de representación de la interfaz es denominada ((método de la frontera inmersa)).Se desarrolla de un código bidimensional dentro del cual se implementa tanto el método original de Uhlmann como modi ficaciones propuestas en la literatura cuyo objetivo es mejorar la representación del sólido dentro del fluido y modelar las interacciones entre sólidos. El código es sometido a una serie de validaciones que evidencian falencias y aciertos dentro del programa.Destacan una sobrestimación del arrastre y la sustentación cuyas causas aúnno logran ser determinadas y un ocasional enlazamiento entre sólidos quecolisionan que evita la representación de ciertos fenómenos físicos de interés.Se expone la discretización para una versión tridimensional del código y una maqueta de éste, a partir de la cual se presentan resultados preliminares que si bien no son capaces de representar la física del problema, muestran un avance concreto en pos del desarrollo de una herramienta capaz de representar suspensiones densas más cercanas a la realidad.
A research is made regarding numerical methods available to study particulate flows, focusing on dense solid-liquid suspensions. From within the found approaches the method from Uhlmann (2005) is selected which consists in a modi ed Navier-Stokes equation that contains an extra term that represents the effects of a solid boundary over the fluid. Such an approach is called the ((immersed boundary method)). A two-dimensional code has been developed where both the original formulation and some variations suggested in the literature are implemented, whose objective is to improve the representation of the particle's boundary and to model the solid-solid interactions. Validation cases are run in order to show the program's shortcomings and strenghts. Both the drag and the lift are overestimated when the particle is moving and its causes are yet to be found. Also it's been found that occasionally the solids get stuck together as they collide instead of bouncing off which avoids certain physical phenomena from appearing.The discretization procedure for the tridimensional version of the code is shown and an outline for the code is developed, from it, preliminar results are obtained that, even though they fail to reproduce the expected physics of the problem, show a concrete advance towards the development of a tool capable of representing the solid suspensions in conditions closer to reality.
A research is made regarding numerical methods available to study particulate flows, focusing on dense solid-liquid suspensions. From within the found approaches the method from Uhlmann (2005) is selected which consists in a modi ed Navier-Stokes equation that contains an extra term that represents the effects of a solid boundary over the fluid. Such an approach is called the ((immersed boundary method)). A two-dimensional code has been developed where both the original formulation and some variations suggested in the literature are implemented, whose objective is to improve the representation of the particle's boundary and to model the solid-solid interactions. Validation cases are run in order to show the program's shortcomings and strenghts. Both the drag and the lift are overestimated when the particle is moving and its causes are yet to be found. Also it's been found that occasionally the solids get stuck together as they collide instead of bouncing off which avoids certain physical phenomena from appearing.The discretization procedure for the tridimensional version of the code is shown and an outline for the code is developed, from it, preliminar results are obtained that, even though they fail to reproduce the expected physics of the problem, show a concrete advance towards the development of a tool capable of representing the solid suspensions in conditions closer to reality.
Description
Catalogado desde la version PDF de la tesis.
Keywords
FLUJOS BIFASICOS , METODO DE LA FRONTERA INMERSA , MODELO DE ESFERAS SUAVES , SUSPENSIONES SOLIDAS