Examinando por Materia "Fluid dynamics"
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Ítem Computational Study of Cell Mobility and Transport Phenomena Through Textile Vascular Grafts Using a Multi-Scale Approach(Universidad EAFIT, 2015) Valencia Cardona, Raúl Adolfo; García Ruíz, Manuel Julio; Bustamante Osorno, JohnTextile vascular grafts are biomedical devices that serve as partial replacement of damaged arterial vessels, prevent aneurysms rupture and restore normal blood flow -- It is believed that the success of a textile vascular graft, in the healing process after implantation, is due to the porous micro-structure of the wall -- Among the key properties that take part in the tissue repair process are the type of fabric and degree of porosity and permeability, defining the ability of a well-controlled environment for the neovascularization, nutrient supply, and cellular transport -- Although the transport of fluids through textiles is of great technical interest in biomedical applications, little is known about predicting the micro-flow pattern and the transport and deposition of individual platelets, related with the graft occlusion -- Often, this information is difficult to obtain experimentally both in vivo and in vitro, representing a great deal of research efforts -- The aim of this work is to investigate how the type of fabric, permeability and porosity affect both the local fluid dynamics at several scales and the fluid-particle interaction among platelets in textile grafts with an anastomosis of end-to-end configuration -- Two types of samples were analyzed: woven and electrospun, this last one has been manufactured -- This study involves both experimental and computational tests -- The experimental tests were performed to characterize the permeability and porosity under static conditions -- The computational tests are based on a multiscale approach where the fluid flow was solved with the Finite Element Method and the discrete particles were solved with the Molecular Dynamic Method -- The fluid-particle interaction was accomplished in one-, two-, and four-ways, where the blood was considered as a suspension of platelets in plasma -- The textile wall was considered as a porous media with two scales of length: straight tubular structure with porous walls for the macro-domain and representative unit cells of fabric for the micro-domain. Additionally, it presents the implementation of a numerical case that includes one of the main applications of textile vascular grafts to repair Abdominal Aortic Aneurysms (AAA) -- The results have shown that the type of fabric in textile vascular grafts and the degree of porosity and permeability affect the local fluid dynamics and the level of penetration of platelet particles through the graft wall at several length scales, thus indicating their importance as design parameters -- It was found that the permeability is strongly depends on the micro-structure of the fabric, changing the local fluid dynamics and the time of residence of platelets inside the wall -- Moreover, the porous walls cause deviations from Poiseuille flow due to leakage flow through the wall from a macroscopic viewpoint -- Lastly, it was possible to observe that the textile wall with different porosities, acting like a barrier between the blood and an aneurysmal zone, affects the flow pattern, the number of platelets adhered to the artificial surface and the time of residence of platelets into the aneurysmal zone -- In conclusion, predicting the flow pattern and the mobility of blood cells through the textile wall before the graft is manufactured, the development of new textile grafts can be improvedÍtem Coupled CFD Shape Optimization for aerodynamic profiles(Universidad EAFIT, 2015) Giraldo Arias, Santiago; García Ruíz, Manuel JulioThe present document deals with the optimization of shape of aerodynamic profiles -- The objective is to reduce the drag coefficient on a given profile without penalising the lift coefficient -- A set of control points defining the geometry are passed and parameterized as a B-Spline curve -- These points are modified automatically by means of CFD analysis -- A given shape is defined by an user and a valid volumetric CFD domain is constructed from this planar data and a set of user-defined parameters -- The construction process involves the usage of 2D and 3D meshing algorithms that were coupled into own- code -- The volume of air surrounding the airfoil and mesh quality are also parametrically defined -- Some standard NACA profiles were used by obtaining first its control points in order to test the algorithm -- Navier-Stokes equations were solved for turbulent, steady-state ow of compressible uids using the k-epsilon model and SIMPLE algorithm -- In order to obtain data for the optimization process an utility to extract drag and lift data from the CFD simulation was added -- After a simulation is run drag and lift data are passed to the optimization process -- A gradient-based method using the steepest descent was implemented in order to define the magnitude and direction of the displacement of each control point -- The control points and other parameters defined as the design variables are iteratively modified in order to achieve an optimum -- Preliminary results on conceptual examples show a decrease in drag and a change in geometry that obeys to aerodynamic behavior principlesÍtem Desarrollo de un modelo predictivo computacional para el diagnóstico de la condición de bombas centrífugas(Universidad EAFIT, 2005) Botero Herrrera, Francisco Javier; Castañeda Heredia, Leonel FranciscoÍtem Diseño del ala para un vehículo aéreo no tripulado(Universidad EAFIT, 2007) Bernal Ortiz, Andrés; Orrego Bustamante, Santiago; Ariza Vélez, NicolásÍtem Estudio de la permeabilidad y la fabricación de materiales compuestos tipo sandwich por RTM(Universidad EAFIT, 2013) Mejía Montero, José Luis; Ossa, Edgar AlexanderÍtem Evaluación de los coefiecientes de velocidad α y β del canal del Laboratorio de Hidráulica de la Universidad EAFIT(Universidad EAFIT, 2011) Gutiérrez Acevedo, Franklin Hernando; Ochoa, Juan FelipePara estimar el valor de los coeficientes de corrección de energía y momentum del canal del laboratorio de hidráulica de la Universidad EAFIT, se realizó una revisión de las diferentes expresiones presentadas desde los años 50’s hasta la información más pertinente y actual sobre el tema -- A partir de esta consulta del estado del arte, se pusieron a punto los equipos de traslación y toma de datos del canal de laboratorio de hidráulica de la Universidad EAFIT, donde se tomaron datos de velocidades puntuales en diferentes puntos de la sección del canal para diferentes caudales -- Utilizando la aplicación computacional MATLAB, mediante el comando contourf, se interpolaron los datos y diagramaron los gráficos de las Isotacas que corresponden a las líneas de igual velocidad, con el objeto de conocer la distribución de velocidad en el canal para los caudales presentados en éste trabajo -- Con estos resultados se determinó la forma de distribución de velocidad para el canal, la influencia de la rugosidad del fondo del canal y se estimaron matemáticamente los coeficientes de corrección de velocidad para las ecuaciones de energía y momentum, comparándolos con los valores calculados con las fórmulas presentadas en la literatura -- Entre los valores encontrados de los coeficientes de corrección de velocidad para el canal de hidráulica de la Universidad EAFIT, y los valores calculados utilizando expresiones de la literatura, se evidenció una diferencia de 2% en promedioÍtem Fixed grid meshing implementation for interactive analysis(Universidad EAFIT, 2012) Duque Lombana, Juan Fernando; García Ruiz, Manuel JulioÍtem 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 JulioA 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 literatureÍtem Interactive CFD simulations(Universidad EAFIT, 2007) Duque Lombana, Juan Fernando; García Ruíz, Manuel JulioThis project is about the development of an implementable Interactive Computer Fluid Dynamics methodology -- The range of this work begins with an overview of the current status of computational fluid dynamics simulation software and methodologies, continues with an introduction to what interactive and interactivity mean, develops an all original interactive CFD methodology to follow for the solution of fluid scenarios and finally, the description of the implementation of an interactive solver for CFD using the earlier developed methodology -- The project was developed entirely at the EAFIT University’s Applied Mechanics Laboratory in Medellin and is part of a collaboration effort in companionship with the University of Aberta in Canada and Los Andes University in Bogota, ColombiaÍtem Interactive parallel fluid solver using the Lattice-Boltzmann method and CUDA(Universidad EAFIT, 2010) Gutiérrez Mazo, Jorge Mario; García Ruíz, Manuel JulioParticle methods have been gaining momentum in the Computational Fluid Dynamics world, for their computational simplicity and inherent parallelism -- This has lead the field to jump to new hardware technologies that exploit the parallelism in a whole new way -- This project is an interactive parallel implementation of the Lattice Boltzmann Method that runs on a hyper parallel architecture as a modern GPU and uses CUDA technology for its implementation -- First the mathematical concepts of the method are introduced, then the implementation is done using the SIMD paradigm, to later on attack the visualization and interactivity simple wayÍtem Low altitude wind simulation over mount saint helens using NASA SRTM digital terrain model(2007-01-01) Garcia, M.J.; Boulanger, P.; Garcia, M.J.; Boulanger, P.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecánica AplicadaOn February 11, 2000, the Shuttle Radar Topography Mission (SRTM) was launched into space as part of one of the pay load of the Shuttle Endeavor. Using a new radar sweeping technique most of the Earth's surfaces was digitized in 3D in approximately 10 days. SRTM acquired enough data during its mission to obtain a near-global high-resolution database of the Earth's topography. This paper describe how this revolutionary data set can be used to simulate anywhere around the Earth low altitude wind conditions for various atmospheric conditions. More specifically, we will describe the various processing steps necessary to convert this high-resolution terrain model provided by the SRTM database into a Computational Fluid Dynamic (CFD) volumetric mesh that is compatible with an open source CFD solver called OpenFOAM running in parallel on large West-Grid supercomputers. This work is the result of a new virtual wind-tunnel under development at the University of Alberta. In the paper, we present wind flow over the MountSaint Helens in the United States for a simple wind flow boundary condition. © 2006 IEEE.Ítem Prediction of multiphase flow in pipelines: literature review(Universidad EAFIT, 2015-08-14) Jerez-Carrizales, M.; Jaramillo, J. E.; Fuentes, D.; Universidad Industrial de Santander; Universidad Industrial de Santander; Universidad Industrial de SantanderÍtem Pruebas de comportamiento de las Turbinas Francis(Universidad EAFIT, 2007) Martínez Escobar, María Paulina; Pineda Botero, Fabio AntonioÍtem Turbulencia en dos dimensiones y su cascada inversa de energía(Universidad EAFIT, 2017) Hernández Arboleda, Sebastián; Isaza Betancourt, Juan Camilo