Examinando por Materia "Hydrodynamics"

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    Análisis de sensibilidad a un modelo de transporte de sedimentos: Golfo de Urabá, Colombia
    (Universidad EAFIT, 2011) Velásquez Montoya, Liliana; Escobar Sierra, Carlos Alejandro
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    Development of structural debris flow fragility curves (debris flow buildings resistance) using momentum flux rate as a hazard parameter
    (Elsevier B.V., 2018-05-18) Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Societal risks associated with debris flow hazards are significant and likely to escalate due to global population growth trends and the compounding effects of climate change. Quantitative risk assessment methods (QRA) provide a means of anticipating the likely impacts and consequences of settlement in areas susceptible to landslide activity and are increasingly being used to inform land use decisions that seek to increase disaster resilience through mitigation and/or adaptation. Current QRA methods for debris flow hazards are based primarily on empirical vulnerability functions that relate hazard intensity (depth, velocity, etc.) to expected levels of loss for a given asset of concern, i.e. most of current methods are dedicated to loss-intensity relations. Though grounded in observed cause-effect relationships, empirical vulnerability functions are not designed to predict the capacity of a building to withstand the physical impacts of a debris flow event, or the related uncertainties associated with modelling building performance as a function of variable debris flow parameters. This paper describes a methodology for developing functions that relate hazard intensity to probability of structural damage, i.e., fragility functions, rather than vulnerability functions, based on the combined hydrodynamic forces of a debris flow event (hazard level) and the inherent structural resistance of building typologies that are common in rural mountainous settings (building performance). Hazard level includes a hydrodynamic force variable (FDF), which accounts for the combined effects of debris flow depth and velocity, i.e. momentum flux (hv2), material density (?) and related flow characteristics including drag (Cd) and impact coefficient (Kd). Building performance is measured in terms of yield strength (Ay), ultimate lateral capacity (AU) and weight to breadth ratios (W/B) defined for a portfolio building types that are common in mountain settlements. Collectively, these model parameters are combined using probabilistic methods to produce building-specific fragility functions that describe the probability of reaching or exceeding successive thresholds of structural damage over a range of hazard intensity values, expressed in terms of momentum flux. Validation of the proposed fragility model is based on a comparison between model outputs and observed cause-effect relationships for recent debris flow events in South Korea and in Colombia. Debris flow impact momentum fluxes, capable of resulting in complete damage to unreinforced masonry buildings (URM) in those regions are estimated to be on the order of 24 m3/s2, consistent with field-based observations. Results of our study offer additional capabilities for assessing risks associated with urban growth and development in areas exposed to debris flow hazards. © 2018 Elsevier B.V.
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    Ítem
    Development of structural debris flow fragility curves (debris flow buildings resistance) using momentum flux rate as a hazard parameter
    (Elsevier B.V., 2018-05-18) Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Mecánica Aplicada
    Societal risks associated with debris flow hazards are significant and likely to escalate due to global population growth trends and the compounding effects of climate change. Quantitative risk assessment methods (QRA) provide a means of anticipating the likely impacts and consequences of settlement in areas susceptible to landslide activity and are increasingly being used to inform land use decisions that seek to increase disaster resilience through mitigation and/or adaptation. Current QRA methods for debris flow hazards are based primarily on empirical vulnerability functions that relate hazard intensity (depth, velocity, etc.) to expected levels of loss for a given asset of concern, i.e. most of current methods are dedicated to loss-intensity relations. Though grounded in observed cause-effect relationships, empirical vulnerability functions are not designed to predict the capacity of a building to withstand the physical impacts of a debris flow event, or the related uncertainties associated with modelling building performance as a function of variable debris flow parameters. This paper describes a methodology for developing functions that relate hazard intensity to probability of structural damage, i.e., fragility functions, rather than vulnerability functions, based on the combined hydrodynamic forces of a debris flow event (hazard level) and the inherent structural resistance of building typologies that are common in rural mountainous settings (building performance). Hazard level includes a hydrodynamic force variable (FDF), which accounts for the combined effects of debris flow depth and velocity, i.e. momentum flux (hv2), material density (?) and related flow characteristics including drag (Cd) and impact coefficient (Kd). Building performance is measured in terms of yield strength (Ay), ultimate lateral capacity (AU) and weight to breadth ratios (W/B) defined for a portfolio building types that are common in mountain settlements. Collectively, these model parameters are combined using probabilistic methods to produce building-specific fragility functions that describe the probability of reaching or exceeding successive thresholds of structural damage over a range of hazard intensity values, expressed in terms of momentum flux. Validation of the proposed fragility model is based on a comparison between model outputs and observed cause-effect relationships for recent debris flow events in South Korea and in Colombia. Debris flow impact momentum fluxes, capable of resulting in complete damage to unreinforced masonry buildings (URM) in those regions are estimated to be on the order of 24 m3/s2, consistent with field-based observations. Results of our study offer additional capabilities for assessing risks associated with urban growth and development in areas exposed to debris flow hazards. © 2018 Elsevier B.V.
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    Estuarine Light Attenuation Modelling Towards Improved Management of Coastal Fisheries
    (SPRINGER, 2019-01-01) Tosic M.; Martins F.; Lonin S.; Izquierdo A.; Restrepo J.D.; Universidad EAFIT. Departamento de Ingeniería; Ciencias del Mar
    The ecosystem function of local fisheries holds great societal importance in the coastal zone of Cartagena, Colombia, where coastal communities depend on artisanal fishing for their livelihood and health. These fishing resources have declined sharply in recent decades partly due to issues of coastal water pollution. Mitigation strategies to reduce pollution can be better evaluated with the support of numerical hydrodynamic models. To model the hydrodynamics and water quality in Cartagena Bay, significant consideration must be dedicated to the process of light attenuation, given its importance to the bay’s characteristics of strong vertical stratification, turbid surface water plumes, algal blooms and hypoxia. This study uses measurements of total suspended solids (TSS), turbidity, chlorophyll-a (Chla) and Secchi depth monitored in the bay monthly over a 2-year period to calculate and compare the short-wave light extinction coefficient (Kd) according to nine different equations. The MOHID-Water model was used to simulate the bay’s hydrodynamics and to compare the effect of three different Kd values on the model’s ability to reproduce temperature profiles observed in the field. Simulations using Kd values calculated by equations that included TSS as a variable produced better results than those of an equation that included Chla as a variable. Further research will focus on evaluating other Kd calculation methods and comparing these results with simulations of different seasons. This study contributes valuable knowledge for eutrophication modelling which would be beneficial to coastal zone management in Cartagena Bay. © 2019, Springer Nature Switzerland AG.
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    Ítem
    Implementation of the Moving Particle Semi-implicit method to predict the drag resistance coefficient on 2D
    (Universidad EAFIT, 2016) Pérez Gutiérrez, Carlos Andrés; García Ruíz, Manuel Julio
    A dam break problem and the flow around a 2D submerged body on different scenarios were solved with the original Moving Particle Semi-implicit (MPS) method proposed by Koshizuka and Oka in 1996 -- The results of this study showed that although the original method reproduces the free surface of the fluid on the dam break computation, it can not accurately compute the pressure distribution over the submerged bodies -- It was found that the free surface was inaccurate when negative pressures were present in the particle domain -- Also, when modelling the interaction of a solid immersed in a fluid, the simulation exhibited stability issues and solid penetration -- Several modifications of the original MPS were studied, implemented and tested -- This thesis proposes a modified Moving Particle Semi-implicit (MPS)method for modelling immerse bodies in an free surface flow -- The MPS method is based on the prediction-correction calculation of the velocity field based on the Helmhotz-Hodge decomposition -- Initially the predicted velocity is calculated based on the viscous and external forces terms and then corrected by the gradient of the pressure which is obtained by the solution of the Poisson Pressure’s equation – This thesis shows how small variations in the source term of the Poisson Pressure’s equation can destabilise or stabilise simulations -- One of the main result of this research is an improved stability by means of a reformulation of the Poisson Pressure equation and the aid of relaxation factors -- Also, the pressure gradient was computed for non free surface particles only -- The results show that, although pressure fluctuations were still present, good results were obtained when compared the drag coefficient to the reported values in the literature
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    Influence of energy consumption on battery sizing of electric fluvial vessels: a Colombian Case Study
    (Institute of Electrical and Electronics Engineers Inc., 2020-09-12) Giraldo, E.; Gaviria, Gregorio; Betancur E.; Gómez, G.O.; Mejá-Gutiérrez, R.; Giraldo, E.; Gaviria, Gregorio; Betancur E.; Gómez, G.O.; Mejá-Gutiérrez, R.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
    Electric vessels represent a sustainable solution for fluvial mobility. However, their energy demand is higher compared to terrestrial vehicles, so that, increasing the hydrodynamic efficiency is mandatory.
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    Metodología para simular la dinámica marina en el mar Caribe usando DELFT3D
    (Universidad EAFIT, 2015) Ruíz Sarrazola, David Alejandro; Escobar Sierra, Carlos Alejandro
    Se desarrolló una metodología para simular la hidrodinámica del mar Caribe -- El mar Caribe es una zona de vital importancia para los países de la región Caribe debido a la presencia de recursos naturales y ubicación estratégica -- Sin embargo la falta de estaciones de monitoreo y las políticas poco claras respecto al manejo de la información disponible, dificultan el desarrollo de proyectos y estudios que buscan explotar y/o proteger estos recursos, como la construcción de infraestructura y la mitigación de la erosión costera -- Aunque se han realizados distintos estudios que han contribuido a la caracterización de la dinámica marina del Caribe, estos se encuentran limitados en su cobertura espacial y temporal -- Como alternativa para superar estos inconvenientes se han desarrollado distintos modelos numéricos para reproducir las corrientes, el oleaje y las mareas del Caribe, sin embargo los modelos desarrollados consideran estos procesos de forma separada, o solo consideran uno de ellos, despreciando sus interacciones -- Lo anterior conllevo a plantear una metodología de simulación para la dinámica marina del mar Caribe que considere las corrientes, oleaje y mareas de forma simultánea y sus interacciones -- Las simulaciones se realizaron utilizando la plataforma DELFT3D que permite acoplar la hidrodinámica, el oleaje y los fenómenos de transporte -- El modelo también considera la descarga de los principales afluentes del Caribe, forzamientos atmosféricos, un modelo de intercambio de calor por la superficie libre y las fuerzas gravitacionales sobre las mareas -- Se realizó un análisis detallado de las distintas fuentes de información disponibles para meteorología y batimetría, determinando la precisión de cada una en distintas zonas y épocas para el área de estudio -- El modelo fue calibrado y validado mediante comparaciones con datos medidos, las comparaciones se realizaron para las dos épocas climáticas características del Caribe en diferentes años -- Se analizó la influencia de procesos, parámetros físicos y numéricos sobre el desempeño del modelo, para esto se utilizaron parámetros estadísticos que permitieron determinar que el modelo se puede calificar entre excelente y razonable, de acuerdo a lo encontrado en la literatura -- El modelo fue utilizado para generar los datos de condiciones de frontera para un modelo de menor escala en la región de Cartagena, con el objetivo de modelar el transporte de sedimentos en esta zona -- El acoplamiento de los dos modelos permitió reproducir de forma correcta la hidrodinámica de la zona, con un desempeño entre bueno y razonable de acuerdo a la literatura -- Por último el modelo fue acoplado con el modelo de pronóstico meteorológico GFS como herramienta para pronosticar el comportamiento de la hidrodinámica en el Caribe
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    Simulación de la hidrodinámica marina en la región de Cartagena con aplicaciones al transporte de sedimentos
    (Universidad EAFIT, 2015) Uribe Suárez, Diego Alejandro; Escobar Sierra, Carlos Alejandro
    Se realizaron simulaciones numéricas de la dinámica marina en la región de Cartagena entre los sectores conocidos como Galerazamba (Norte) y Bocachica (Sur) aplicadas al estudio del transporte de sedimentos -- El fenómeno de la erosión costera afecta negativamente el desarrollo de esta región tanto a nivel económico como social, debido a problemáticas relacionadas con la pérdida de tierras de importante utilidad para actividades de turismo y habitación humana, así como el deterioro de diferentes infraestructuras físicas -- Sin embargo, no se cuenta con muchos estudios realizados en esta zona que permitan un total entendimiento del fenómeno, y existe poca información y pocas estaciones de monitoreo de la dinámica marina de la zona (generador principal del transporte de sedimentos) -- Lo anterior motivó la realización de simulaciones numéricas de la dinámica marina aplicadas al estudio del transporte de sedimentos -- Las simulaciones se realizaron en la plataforma Delft3D desarrollada por WL Delft Hydraulics, en la que se acoplan simultáneamente la hidrodinámica, el oleaje y el transporte de sedimentos -- Las simulaciones realizadas consideran además forzamientos externos debidos a la marea, el oleaje y la atmosfera, para los cuales se realizó un análisis detallado de distintas fuentes de información batimétrica, topográfica y meteorológica disponibles, determinando la precisión de cada una de estas para diferentes zonas y épocas climáticas -- El desempeño de las simulaciones se evaluó al confrontar el ajuste entre el oleaje direccional y las corrientes modeladas y medidas en las dos épocas climáticas características de la región (seca y lluviosa) -- En ambas campañas de medición se combinaron estaciones de medición fijas y móviles, permitiendo así ampliar la resolución temporal y espacial de las observaciones -- Los parámetros estadísticos utilizados en la evaluación de las simulaciones indicaron que éstas lograron una representación entre razonable y buena de la dinámica marina en la región de Cartagena -- Una vez verificado el buen desempeño de las simulaciones, se procedió en primera instancia a determinar el patrón característico de las corrientes y del oleaje en cada una de las épocas climáticas de la región, encontrándose que para ambas temporadas las corrientes en la mayoría del dominio se dirigen hacia el sur, y el oleaje viene predominantemente del noreste (NE) -- Se encontró que los cambios en la magnitud de las corrientes de una temporada a otra fueron mínimos con una velocidad media de las corrientes de 0.12 m/s en temporada húmeda, y una época seca que se caracterizó por presentar regímenes de oleaje de mayor intensidad con una altura de ola media de 0.83 m. -- Posteriormente se realizó el acoplamiento entre las simulaciones numéricas realizadas y el módulo de transporte de sedimentos presente en Delft3D -- Para la implementación de este módulo se utilizó la información recolectada en la campaña de medición llevada a cabo en Octubre de 2013, se compararon concentraciones de sedimentos en suspensión medidas y modeladas, donde se encontró que la simulación construida logró reproducirlas de forma acertada en la mayoría de la región -- Luego de determinar un aceptable comportamiento de las simulaciones, se realizaron balances de sedimentos a lo largo de la línea de costa a partir de los datos modelados, con el fin de determinar zonas de erosión y sedimentación para las épocas climáticas seca y húmeda, así como para el caso de un evento extremo -- Los resultados mostraron que las simulaciones lograron reproducir, para una escala temporal de días, tendencias erosivas al norte del corregimiento de Galerazamba, en los alrededores de Bocacanoas, en el norte de Punta Canoas, Bocagrande y sectores del norte de Tierrabomba, mientras que la acumulación de sedimentos se presentó en los alrededores de la parte sur de Lomarena, sur de Punta Canoas y el Laguito, lo cual concuerda con lo reportado en la literatura, corroborando que las simulaciones llevadas a cabo representan una alternativa de gran utilidad para el estudio del transporte de sedimentos en la región de Cartagena
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    Study of the state a Francis turbine
    (Politechnika Gdanska, Wydzial Oceanotechniki i Okretownictwa, 2013-04-01) Zóltowski, M.; Zóltowski, B.; Castaneda, L.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    This paper presents a methodology to evaluate the technical state of a Francis turbine by shaft rotor dynamic simulation. There are several rotor dynamic criteria that define the technical state of a turbo-machine. To feed the shaft rotor dynamic model this delivers the required information to accomplish the technical assessment. The numerical rotor dynamic model uses as input, the field forces obtained by the fluid-solid interaction analysis undertaken over the blades of the runner. The rotor dynamic numerical simulations allow to determinate the record-in-time of the displacements of any point along the shaft. This information is relevant for diagnosis tasks, because it is possible to decompose it spectrally and to estimate the severity of the vibrations. Comparing the results of the numerical model against those obtained from machines that operates under normal conditions, it is possible to determinate the technical state of the turbo-machine. This allows studying the stability of the turbine working on several operation ranges. A Francis turbine is a very complex machine that involves many physical phenomena of different nature. In this way, the hydraulic input forces needed by the rotor dynamic model should not be assumed but calculated directly from the fluid interaction over the turbine structure.
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    Triaxial deformation behavior of bituminous mixes
    (ASCE-AMER SOC CIVIL ENGINEERS, 2010-02-01) Ossa, E. A.; Deshpande, V. S.; Cebon, D.; Ossa, E. A.; Deshpande, V. S.; Cebon, D.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    The triaxial compressive response of bituminous mixes with volume fractions of aggregate in the range 52 to 85% was investigated over a wide range stresses and strain rates. The types of loadings considered include triaxial monotonic constant stress and constant applied strain rate, as well as creep recovery, continuous cyclic, and stress pulse train loadings. The mixes with a "fully dense" aggregate skeleton were found to dilate under all loading conditions and the creep response of the mixes was dependent on both the deviatoric and hydrostatic stresses. By contrast, recovery was found to occur under zero applied deviatoric stresses with the recovery rate only dependent on the "recoverable strain" and independent of any superimposed hydrostatic stress. Continuous and pulse loading cyclic stress-controlled tests showed that the response of the mixes was governed by the mean applied deviatoric stress in the continuous cyclic tests while strain recovery was important in the pulse loading tests. A phenomenological constitutive model was proposed to fit the measured triaxial response of the bituminous mixes and shown to capture the measurements over all the triaxial stress states and loading time histories investigated here. Furthermore, the model was extended to capture the temperature dependence of the mixtures which is governed by the temperature dependence of the bitumen binder. © 2010 ASCE.