Thesis SIMULACIÓN NUMÉRICA DE TRANSPORTE DE FONDO CON DOBLE ACOPLAMIENTO EN UN CANAL TURBULENTO
Date
2021-05
Authors
NEIRA JAEGER, JOAQUÍN
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Abstract
El transporte de sedimentos en canales y ríos es el proceso mediante el cual partículas de distintos tamaños, inmersas en un fluido, son desplazadas producto de las fuerzas ejercidas por este último. El estudio de este fenómeno durante las últimas décadas ha tenido un enfoque mayormente experimental, dejando la teoría en un segundo plano, por lo cual el proceso aún no es comprendido en su totalidad.
Existen dos formas de transporte de sedimentos. La primera es el transporte en suspensión, en el cual las partículas de menor tamaño se mueven suspendidas en el fluido, lejos del lecho. La segunda es el transporte de fondo, en el cual las partículas de mayor tamaño, presentes en el fondo del cauce, son movidas deslizando, rodando, o incluso dando saltos, lo que se conoce como saltación. Esta última forma de transporte es el objeto de estudio de este trabajo.
Para realizar el estudio del arrastre de fondo, se ha desarrollado un modelo computacional en OpenFOAM, consistente de una fase continua (fluido), que simula un flujo turbulento, y una fase dispersa (partículas), que es dividida en tres submodelos: vuelo libre (aplicación de fuerzas hidrodinámicas ejercidas por el flujo sobre la partícula), colisión con el fondo, y colisión entre partículas. Se ha considerado, además, el acoplamiento de dos vías entre las fases continua y dispersa, por lo cual las partículas inmersas en el fluido también afectan su comportamiento.
El modelo se ha validado utilizando valores experimentales presentes en la literatura, y ha permitido obtener resultados respecto al efecto, tanto en el flujo como en las partículas, de aumentar la concentración de partículas presentes en el flujo. Por último, se han estudiado los recursos computacionales utilizados en cada caso simulado
The transport of sediments in canals and rivers is the process by which particles of different sizes,immersed in a fluid, are displaced due to the forces exerted by the latter. The study of this phenomenon during the last decades has had a mostly experimental approach, leaving the theory in the background, so the process is not yet fully understood. There are two forms of sediment transport. The first is suspended load, in which smaller particles move suspended in the fluid, away from the bed. The second is the bed load, in which the larger particles, present in the bottom of the channel, are moved by sliding, rolling, or even hopping, what is known as saltation. This last form of transport is the object of study of this work. To carry out the study of bed load, a computational model has been developed in OpenFOAM, consisting of a continuous phase (fluid), which simulates a turbulent flow, and a dispersed phase (particles), which is divided into three submodels: free flight (application of hydrodynamic forces exerted by the flow on the particle), collision with the bottom, and collision between particles. In addition, the two-way coupling between the continuous and dispersed phases has been considered, whereby the particles immersed in the fluid also affect their behavior. The model has been validated using experimental values present in the literature, and has allowed us to obtain results regarding the effect, both in the flow and in the particles, of increasing the concentration of particles present in the flow. Finally, the computational resources used in each simulated case have been studied
The transport of sediments in canals and rivers is the process by which particles of different sizes,immersed in a fluid, are displaced due to the forces exerted by the latter. The study of this phenomenon during the last decades has had a mostly experimental approach, leaving the theory in the background, so the process is not yet fully understood. There are two forms of sediment transport. The first is suspended load, in which smaller particles move suspended in the fluid, away from the bed. The second is the bed load, in which the larger particles, present in the bottom of the channel, are moved by sliding, rolling, or even hopping, what is known as saltation. This last form of transport is the object of study of this work. To carry out the study of bed load, a computational model has been developed in OpenFOAM, consisting of a continuous phase (fluid), which simulates a turbulent flow, and a dispersed phase (particles), which is divided into three submodels: free flight (application of hydrodynamic forces exerted by the flow on the particle), collision with the bottom, and collision between particles. In addition, the two-way coupling between the continuous and dispersed phases has been considered, whereby the particles immersed in the fluid also affect their behavior. The model has been validated using experimental values present in the literature, and has allowed us to obtain results regarding the effect, both in the flow and in the particles, of increasing the concentration of particles present in the flow. Finally, the computational resources used in each simulated case have been studied
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Keywords
TRANSPORTE DE SEDIMENTOS , HIDRODINAMICA , DINAMICA DE FLUIDOS , OPENFOAM
