Examinando por Autor "Uribe, David"
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Ítem Determining the limits of geometrical tortuosity from seepage flow calculations in porous media(WILEY-VCH Verlag, 2014) Uribe, David; Osorno, María; Sivanesapillai, Rakulan; Steeb, Holger; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAERecent investigations have found a distinct correlation of effective properties of porous media to sigmoidal functions, where one axis is the Reynolds number Re and the other is the effective property dependent of Re, Θ = S (Re) -- One of these properties is tortuosity -- At very low Re (seepage flow), there is a characteristic value of tortuosity, and it is the upper horizontal asymptote of the sigmoidal function -- With higher values of Re (transient flow) the tortuosity value decreases, until a lower asymptote is reached (turbulent flow) -- Estimations of this parameter have been limited to the low Reynolds regime in the study of porous media -- The current state of the art presents different numerical measurements of tortuosity, such as skeletization, centroid binding, and arc length of streamlines -- These are solutions for the low Re regime. So far, for high Re, only the arc length of stream lines has been used to calculate tortuosity -- The present approach involves the simulation of fluid flow in large domains and high Re, which requires numerous resources, and often presents convergence problems -- In response to this, we propose a geometrical method to estimate the limit of tortuosity of porous media at Re → ∞, from the streamlines calculated at low Re limit -- We test our method by calculating the tortuosity limits in a fibrous porous media, and comparing the estimated values with numerical benchmark results -- Ongoing work includes the geometric estimation of different intrinsic properties of porous mediaÍtem Estimation of large domain Al foam permeability by Finite Difference methods(WILEY-VCH Verlag, 2013) Osorno, María; Steeb, Holger; Uribe, David; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEClassical methods to calculate permeability of porous media have been proposed mainly for high density (e.g. granular) materials -- These methods present shortcomings in high porosity, i.e. high permeability media (e.g. metallic foams) -- While for dense materials permeability seems to be a function of bulk properties and occupancy averaged over the volume, for highly porous materials these parameters fail to predict it -- Several authors have attacked the problem by solving the Navier-Stokes equations for the pressure and velocity of a liquid flowing through a small domain (Ωs) of aluminium foam and by comparing the numerical results with experimental values (prediction error approx. 9%) -- In this article, we present calculations for much larger domains (ΩL) using the Finite Difference (FD) method, solving also for the pressure and velocity of a viscous liquid flowing through the Packed Spheres scenario -- The ratio Vol(ΩL)/Vol(Ωs) is around 103 -- The comparison of our results with the Packed Spheres example yields a prediction error of 5% for the intrinsic permeability -- Additionally, numerical permeability calculations have been performed for Al foam samples -- Our geometric modelling of the porous domain stems from 3D X-ray tomography, yielding voxel information, which is particularly appropriate for FD -- Ongoing work concerns the reduction in computing times of the FD method, consideration of other materials and fluids, and comparison with experimental dataÍtem Finite difference calculations of permeability in large domains in a wide porosity range.(Springer Berlin Heidelberg, 2015-08) Osorno, Maria; Uribe, David; Ruiz Salguero, Oscar; Holger, Steeb; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEDetermining effective hydraulic, thermal, mechanical and electrical properties of porous materials by means of classical physical experiments is often time-consuming and expensive. Thus, accurate numerical calculations of material properties are of increasing interest in geophysical, manufacturing, bio-mechanical and environmental applications, among other fields. Characteristic material properties (e.g. intrinsic permeability, thermal conductivity and elastic moduli) depend on morphological details on the porescale such as shape and size of pores and pore throats or cracks. To obtain reliable predictions of these properties it is necessary to perform numerical analyses of sufficiently large unit cells. Such representative volume elements require optimized numerical simulation techniques. Current state-of-the-art simulation tools to calculate effective permeabilities of porous materials are based on various methods, e.g. lattice Boltzmann, finite volumes or explicit jump Stokes methods. All approaches still have limitations in the maximum size of the simulation domain. In response to these deficits of the well-established methods we propose an efficient and reliable numerical method which allows to calculate intrinsic permeabilities directly from voxel-based data obtained from 3D imaging techniques like X-ray microtomography. We present a modelling framework based on a parallel finite differences solver, allowing the calculation of large domains with relative low computing requirements (i.e. desktop computers). The presented method is validated in a diverse selection of materials, obtaining accurate results for a large range of porosities, wider than the ranges previously reported. Ongoing work includes the estimation of other effective properties of porous media.Ítem Finite Element Modeling of Composite Materials using Kinematic Constraints(Universidad EAFIT, 2009-12-01) E. Ruiz, Oscar; Barschke, Merlin; Uribe, David; Jensen, Jens; López, Carlos; Universidad EAFITÍtem Finite Element Modeling of Composite Materials using Kinematic Constraints(Universidad EAFIT, 2009-12) Barschke, Merlin; Uribe, David; Ruíz, Óscar E.; Jensen, Jens; López, Carlos; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEEl propósito de este artículo es presentar simulaciones del comportamiento de materiales compuestos basado en restricciones cinemáticas entre las mismas fibras y entre las fibras y la resina circundante -- En la revisión de literatura, los autores han encontrado que las restricciones cinemáticas no han sido plenamente explotadas para modelar materiales compuestos, probablemente debido a su alto costo computacional -- El propósito de este artículo es exponer la implementación y resultados de tal modelo, usando Análisis por Elementos Finitos de restricciones geométricas prescritas a los nodos de la resina y las fibras -- Las descripciones analíticas del comportamiento de materiales compuestos raramente aparecen -- Muchas aproximaciones para describir materiales compuestos en capas son basadas en la teoría de funciones C1 Z y C0Z, tal como la Teoría Clásica de Capas (CLT) -- Estas teorías de funciones contienen significativas simplificaciones del material, especialmente para compuestos tejidos -- Una aproximación hibrida para modelar materiales compuestos con Elementos Finitos (FEA) fue desarrollada por Sidhu y Averill [1] y adaptada por Li y Sherwood [2] para materiales compuestos tejidos con polipropileno de vidrio -- Este artículo presenta un método para obtener valores para las propiedades de los materiales compuestos -- Tales valores son usados para simular las fibras reforzadas tejidas aplicando elementos de capas en el software ANSYS -- El presente modelo requiere menos simplificaciones que las teorías C1Z y C0Z -- En el artículo presente, a diferencia del modelo Li–Sherwood, el tejido es modelado geométricamente -- Una Representación por la Frontera (B-Rep del modelo “Hand”) con genus 1 (con geometría compleja) fue usada para aplicar restricciones geométricas a las capas de resina, fibra, etcétera, mostrando que es apropiada para simular estructuras complejas -- En el futuro, las propiedades no–lineales de los materiales deben ser consideradas, y el trabajo experimental requerido debe ser realizadoÍtem Geometry simplification for modeling of porous materials(2015) Ruíz, Óscar E.; Cadavid, Esteban; Osorno, María C.; Uribe, David; Steeb, Holger; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEPorous and lattice materials have become everpresent in applications such as medicine, aerospace, design, manufacturing, art, entertainment, robotics, material handling, etc -- However, their application is impeded by the uncertainty of their mechanical properties (elongation, torsion, compression moduli, etc.) -- Computational Mechanics of poorus materials is also hindered by the massive geometric data sets that they entail, if their full geometric representations are used -- In response to these limitations, this article presents a truss simplification of a porous material --This simplified representation is usable in computer simulations, instead of the full triangle- or freeform-based Boundary Representations (B-Rep), which produce intractable problems -- This article presents the simplification methodology, along with results of estimation of the stress - strain response of porous material (in this case, Aluminum) -- Our methodology presents itself as a possible alternative in contrast with impossible processing when full data is used -- Follow up work is needed in using the truss methodology for calculating macro-scaleequivalent Young or Poisson moduli, with applications on mechanical designÍtem Microscale Investigations of High Frequency Wave Propagation Through Highly Porous Media(Gesellschaft für Angewandte Mathematik und Mechanik (GAMM), 2012-12-03) Uribe, David; Saenger, Erik; Jänicke, Ralf; Steeb, Holger; Ruiz, O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEÍtem Microscale investigations of highfrequency wave propagation through highly porous media(WILEY-VCH Verlag, 2012-12-03) Uribe, David; Saenger, Erik; Jänicke, Ralf; Steeb, Holger; Ruíz, Oscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEWave propagation in highly porous materials has a well established theoretical background -- Still there are parameters which require complex laboratory experimentation in order to find numerical values -- This paper presents an effective method to calculate the tortuosity of aluminum foam using numerical simulations -- The work flow begins with the acquisition of the foam geometry by means of a micro-CT scanner and further image segmentation and analysis -- The elastodynamic wave propagation equation is solved using a velocity-stress rotated staggered finite-difference technique -- The effective wave velocities are calculated and using the fluid and, aluminum effective properties, the tortuosity is determinedÍtem Numerical analysis of wave propagation in fluid-filled deformable tubes(WILEY-VCH Verlag, 2013-11-29) Uribe, David; Steeb, Holger; Saenger, Erik H.; Kurzeja, Patrick; Ruíz, Óscar; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThe theory of Biot describing wave propagation in fluid saturated porous media is a good effective approximation of a wave induced in a fluid-filled deformable tube -- Nonetheless, it has been found that Biot’s theory has shortcomings in predicting the fast P-wave velocities and the amount of intrinsic attenuation -- These problems arises when complex mechanical interactions of the solid phase and the fluid phase in the micro-scale are not taken into account -- In contrast, the approach proposed by Bernabe does take into account micro-scopic interaction between phases and therefore poses an interesting alternative to Biot’s theory -- A Wave propagating in a deformable tube saturated with a viscous fluid is a simplified model of a porous material, and therefore the study of this geometry is of great interest -- By using this geometry, the results of analytical and numerical results have an easier interpretation and therefore can be compared straightforward -- Using a Finite Difference viscoelastic wave propagation code, the transient response was simulated -- The wave source was modified with different characteristic frequencies in order to gain information of the dispersion relation -- It was found that the P-wave velocities of the simulations at sub-critical frequencies closely match those of Bernabe’s solution, but at over-critical frequencies they come closer to Biot’s solutionÍtem Numerical analysis of wave propagation in fluid-filled deformable tubes(Gesellschaft für Angewandte Mathematik und Mechanik (GAMM), 2013-11-29) Uribe, David; Steeb, Holger; Saenger, Erik H.; Kurzeja, Patrick; Ruiz, O.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEÍtem Relaxed loading conditions for higher order homogenisation approaches(WILEY-VCH Verlag, 2011-12-09) Jänicke, Ralf; Uribe, David; Ruíz, Óscar E.; Steeb, Holger; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThe present paper deals with the formulation of minimal loading conditions for the application of numerical homogenisation techniques, namely the FE methodology -- Based on the set of volume averaging rules connecting the heterogeneous micro and the homogeneous macro scale, the minimal constraints on the deformation of a micro volume are derived for a classical Cauchy as well as for a micromorphic overall continuum theory -- For both cases, numerical studies are included highlighting the main aspects of the proposed procedureÍtem Relaxed loading conditions for higher order homogenisation approaches(Gesellschaft für Angewandte Mathematik und Mechanik (GAMM), 2011-01-01) Jänicke, Ralf; Uribe, David; Ruiz, Oscar Eduardo; Steeb, Holger; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEThe present paper deals with the formul at ion of mi n imal loading conditions for the applicatio n of numerical homogenisa-tion techniques, namely th e FE2methodology. Based on the set of volume averaging rules connecting the het ero geneous micro