Experimental and numerical response of a passive glaucoma drainage device

Glaucoma is the optic nerve damage often associated with an increased intraocular pressure that leads to progressive and irreversible loss of vision. The Ahmed valve is a passive device constructed from two opposed deformable silicone elastomers sheets, commonly used for the regulation of intraocular pressure in patients with glaucoma. In this work the dynamic response of the Ahmed valve to different flow conditions and gravity test of FDA is analyzed. This is carried out by means of the numerical simulation using the Finite Element Method, considering a partitioned Fluid-Structure coupling between the fluid and the structure of the valve. The fluid is described by the incompressible Navier-Stokes equations, written in an arbitrary time dependent coordinate system and the structure is described by a constitutive linear elastic solid assuming large displacements and rotations. In order to decrease the computational cost of the simulation, a reduced order model of the system is also presented. This model is developed using data from a previous characterization process using the partitioned fluid-structure solver. With the aim to validate the numerical simulation, the results are compared with experimental ones.Fil: Sassetti, Fernando. Universidad Nacional de Entre Rios. Facultad de Ingenieria. Departamento de Bioingenieria; ArgentinaFil: Garelli, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico. Centro de Investigación de Métodos Computacionales; ArgentinaFil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico. Centro de Investigación de Métodos Computacionales; Argentin

A Coupling Strategy for a Chimera Method Applied to Thermal Conduction Optimization Problems

The main idea of the Chimera method is to generate independent meshes for the objects present in a computational domain and to couple them by a coupling strategy in order to obtain a unique solution of the system. The method has appealing characteristics that are convenient for applications like simplified mesh generation, moving components, local refinement and optimization. The optimization process is a straightforward application where several objects, each one with its respective mesh, can be moved around without the need to remesh the whole computational domain. Then, different optimization techniques can be used to find the optimum configuration of the system in terms of an objective function. In a previous work (B. Storti et al., “A chimera method based on Dirichlet-Dirichlet coupling and pasting penalization operators”, Mecánica Computacional, vol. XXXIV, 2016), we have presented and validated a Chimera scheme in the finite element context for structured meshes, and we have proven that it has a good convergence rate solving the system iteratively with BiCGStab (BiConjugate Gradient Stabilized method). In the present work, we improve the Chimera method to solve thermal conduction problems on overlapping unstructured meshes and then we test it in several optimization cases. A Dirichlet-Dirichlet coupling imposes the continuity of the unknown on overlapping subdomains and to transfer these values between the multiples domains, a third order interpolation method is used in conjunction with a "pasting" penalization operator. Several numerical examples are also shown in order to validate the proposed interpolation method. Finally a variety of optimization problems are solved under the pyOpt framework, either using gradient-free or gradient based optimizers, running in the CIMEC cluster Seshat (http://www.cimec.org.ar/c3/seshat/equipos.php), where every evaluation test of the objective function is compute on each core. Seshat is a 69 nodes cluster, which has an Infiniband network and a computing power of almost 7 TFLOPS.Publicado en: Mecánica Computacional vol. XXXV, no. 28.Facultad de Ingenierí

Coupling Concept of two Parallel Research Codesfor Two and Three Dimensional Fluid Structure Interaction Analysis

This paper discuss a coupling strategy of two different software packages to provide fluid structure interaction (FSI) analysis. The basic idea is to combine the advantages of the two codes to create a powerful FSI solver for two and three dimensional analysis. The fluid part is computed by a program called PETSc-FEM a software developed at Centro de Investigacion de Metodos Computacionales CIMEC. The structural part of the coupled process is computed by the research code elementary Parallel Solver (ELPASO) of the Technische Universitat Braunschweig, Institut fur Konstruktionstechnik (IK).Fil: Garelli, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Schauer, Marco. Technische Universität Braunschweig; AlemaniaFil: D'elia, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Storti, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Langer, Sabine C.. Technische Universität Braunschweig; Alemani

Adaptive Simulation of the Internal Flow in a Rocket Nozzle

This work is a first step in the understanding of the interaction process between internal shock waves and the flow transition inside of a rocket nozzle that develops during the engine start-up phase or when the nozzle is operated at over-expanded conditions. In many cases, this transition in the flow pattern produces side loads in the nozzle due to an asymmetric pressure distribution on the wall, being harmful for the rocket´s integrity. To understand this phenomenon, a numerical simulation is performed by solving the three-dimensional Euler equations on unstructured tetrahedral meshes. With this model the computational cost to solve the equations significantly increases, therefore parallel processing is required. Also, an unsteady  h-adaptive refinement strategy is used jointly with a StreamlineUpwind Petrov-Galerkin and a discontinuity capturing scheme, both to keep the size of the fluid flow problem bounded and to sharply resolve the shock wave pattern. The mesh adaptation strategy is introduced. Since its performance is a major concern in the solution of unsteady flow problems, some implementation issues about the data structure chosen to represent the mesh are discussed. Average pressure distributions computed at the wall and the axis of thenozzle for various pressure ratios are analyzed based on experimental and numerical results from other authors.Fil: Garelli, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Rios Rodriguez, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Paz, Rodrigo Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; ArgentinaFil: Storti, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones En Metodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones En Metodos Computacionales; Argentin

Reduced model for the thermo-fluid dynamic analysis of a power transformer radiator working in ONAF mode

This work introduces an extension of the semi-analytical reduced model presented in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271–1280 (2016); with the aim of analyzing the thermo-fluid dynamic behavior of a power transformer radiator working in ONAF (Oil Natural Air Forced) mode, considering vertical blowing of the fans. The objective of this research paper is the development of a numerical tool to be used during the design process of power transformers in order to obtain more detailed information about the radiators performance, either they are working in ONAF or ONAN (Oil Natural Air Natural) mode. Since it is observed both in the experimental measurements and in the numerical simulations that not all the radiator panels are blown by a single fan, the reduced model here presented considers a mixed situation wherein the heat is removed by natural convection in a fraction of the radiator while in the rest the heat is removed by forced convection. As a consequence, besides adding to the set of conservation equations introduced in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271– 1280 (2016); those corresponding to the momentum and energy balance for considering forced heat convection transfer, there appears the need of introducing additional equations for coupling the natural and forced heat convection transfer models. The reduced model developed in this work is applied to estimate different characteristic parameters of a power transformer radiator working in ONAF mode, like the oil flow rate, dissipated power, outlet and inlet oil temperatures, among others. The computed results are compared to those obtained by CFD simulations and experimental measurements carried out on an ad-hoc workbench for validation purposes. It is found that the reduced model reproduces with acceptable accuracy the values of the most important design variables at a very low computation cost. In this manner, it can be considered as a reliable and valuable tool in the design of power transformers, allowing to carry out parametric studies.Publicado en: Mecánica Computacional vol. XXXV, no. 4Facultad de Ingenierí

Reduced model for the thermo-fluid dynamic analysis of a power transformer radiator working in ONAF mode

This work introduces an extension of the semi-analytical reduced model presented in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271–1280 (2016); with the aim of analyzing the thermo-fluid dynamic behavior of a power transformer radiator working in ONAF (Oil Natural Air Forced) mode, considering vertical blowing of the fans. The objective of this research paper is the development of a numerical tool to be used during the design process of power transformers in order to obtain more detailed information about the radiators performance, either they are working in ONAF or ONAN (Oil Natural Air Natural) mode. Since it is observed both in the experimental measurements and in the numerical simulations that not all the radiator panels are blown by a single fan, the reduced model here presented considers a mixed situation wherein the heat is removed by natural convection in a fraction of the radiator while in the rest the heat is removed by forced convection. As a consequence, besides adding to the set of conservation equations introduced in G. Ríos Rodriguez et.al., App Thermal Eng, 112:1271– 1280 (2016); those corresponding to the momentum and energy balance for considering forced heat convection transfer, there appears the need of introducing additional equations for coupling the natural and forced heat convection transfer models. The reduced model developed in this work is applied to estimate different characteristic parameters of a power transformer radiator working in ONAF mode, like the oil flow rate, dissipated power, outlet and inlet oil temperatures, among others. The computed results are compared to those obtained by CFD simulations and experimental measurements carried out on an ad-hoc workbench for validation purposes. It is found that the reduced model reproduces with acceptable accuracy the values of the most important design variables at a very low computation cost. In this manner, it can be considered as a reliable and valuable tool in the design of power transformers, allowing to carry out parametric studies.Publicado en: Mecánica Computacional vol. XXXV, no. 4Facultad de Ingenierí

Pedagogias do conflito ambiental: contribuições de uma experiência participativa da formação de professores em um território disputado

We present a first systematization of an in-service teacher training process, arising from the articulation between a socio-territorial organization and a school in the Paraná Delta. This territory of extensive wetlands is crisscrossed by disputes between on one side rural living spaces and islander ways of life and on the other side privatization and transformation into luxury gated communities with serious socio-environmental consequences. We intend to contribute to the understanding of some ways in which these socio-territorial movements can contribute to the pedagogical-didactic frameworks that sustain dialogues between school and communities. In particular, we analyze the contributions to the pedagogization of environmental conflictsPresentamos una primera sistematización de un proceso de formación docente en ejercicio, surgido de la articulación entre una organización socioterritorial y una escuela en el Delta del Paraná. Este territorio de extensos humedales se encuentra atravesado por disputas entre espacios de vida campesina, portadora de modos de vida isleños, y avanzadas de privatización hacia barrios cerrados de lujo con graves consecuencias socioambientales. Pretendemos aportar a la comprensión algunas maneras en las que estos movimientos pueden contribuir a los marcos pedagógico-didácticos que sustentan diálogos entre escuela y comunidades. En particular, analizamos los aportes a la pedagogización de los conflictos ambientales.Apresentamos uma primeira sistematização de um processo de formação de professores em serviço, decorrente da articulação entre uma organização sócio-territorial e uma escola no Delta do Paraná. Esse território de extensas áreas úmidas é atravessado por disputas entre os espaços de vida camponeses com estilos de vida insulares e a privatização para bairros fechados de luxo com sérias conseqüências socioambientais. Pretendemos contribuir para a compreensão de algumas maneiras pelas quais esses movimentos podem contribuir para as estruturas pedagógico-didáticas que sustentam o diálogo entre a escola e as comunidades. Em particular, analisamos as contribuições para a pedagogização de conflitos ambientais

Estudio de escalabilidad del código Code_Saturne en el clúster Pirayú

El presente trabajo tiene como objetivo realizar un estudio de escalabilidad y de desempeño del código computacional Code_Saturne en uno de los clústeres que posee actualmente el CIMEC, Pirayú. Para dicho estudio se propondrá una serie de casos de prueba, correctamente referenciados y validados, contemplando diferentes regímenes fluido dinámicos (laminar y turbulento) para analizar el impacto de los modelos de turbulencia. Para la resolución de estos casos se emplearán tanto mallas estructuradas como no estructuradas satisfaciendo ciertos criterios y niveles de calidad. Para la resolución de los problemas de prueba se utilizará la versión de producción actual del código [5.0.1), analizando el desempeño del mismo mediante la paralelización tanto con OpenMP, como con MPI e híbrida, a los efectos de determinar el balance óptimo entre hilos y procesos a ser ejecutados en cada nodo del clúster. Adicionalmente, se prevé utilizar dos compiladores (GNU, Intel) con el fin de evaluar las optimizaciones que generan para el hardware; y dos bibliotecas de álgebra lineal (OpenBLAS, Intel MKL) para medir su influencia en el tiempo de cómputo. Este primer análisis pretende ser un punto de referencia para la evaluación y comparación de futuras versiones del código, como así también para el caso de actualizaciones de software y/o hardware en los clústeres.Publicado en: Mecánica Computacional vol. XXXV, no. 11Facultad de Ingenierí

Estudio de escalabilidad del código Code_Saturne en el clúster Pirayú

El presente trabajo tiene como objetivo realizar un estudio de escalabilidad y de desempeño del código computacional Code_Saturne en uno de los clústeres que posee actualmente el CIMEC, Pirayú. Para dicho estudio se propondrá una serie de casos de prueba, correctamente referenciados y validados, contemplando diferentes regímenes fluido dinámicos (laminar y turbulento) para analizar el impacto de los modelos de turbulencia. Para la resolución de estos casos se emplearán tanto mallas estructuradas como no estructuradas satisfaciendo ciertos criterios y niveles de calidad. Para la resolución de los problemas de prueba se utilizará la versión de producción actual del código [5.0.1), analizando el desempeño del mismo mediante la paralelización tanto con OpenMP, como con MPI e híbrida, a los efectos de determinar el balance óptimo entre hilos y procesos a ser ejecutados en cada nodo del clúster. Adicionalmente, se prevé utilizar dos compiladores (GNU, Intel) con el fin de evaluar las optimizaciones que generan para el hardware; y dos bibliotecas de álgebra lineal (OpenBLAS, Intel MKL) para medir su influencia en el tiempo de cómputo. Este primer análisis pretende ser un punto de referencia para la evaluación y comparación de futuras versiones del código, como así también para el caso de actualizaciones de software y/o hardware en los clústeres.Publicado en: Mecánica Computacional vol. XXXV, no. 11Facultad de Ingenierí

Estudio de escalabilidad del código Code_Saturne en el clúster Pirayú

El presente trabajo tiene como objetivo realizar un estudio de escalabilidad y de desempeño del código computacional Code_Saturne en uno de los clústeres que posee actualmente el CIMEC, Pirayú. Para dicho estudio se propondrá una serie de casos de prueba, correctamente referenciados y validados, contemplando diferentes regímenes fluido dinámicos (laminar y turbulento) para analizar el impacto de los modelos de turbulencia. Para la resolución de estos casos se emplearán tanto mallas estructuradas como no estructuradas satisfaciendo ciertos criterios y niveles de calidad. Para la resolución de los problemas de prueba se utilizará la versión de producción actual del código [5.0.1), analizando el desempeño del mismo mediante la paralelización tanto con OpenMP, como con MPI e híbrida, a los efectos de determinar el balance óptimo entre hilos y procesos a ser ejecutados en cada nodo del clúster. Adicionalmente, se prevé utilizar dos compiladores (GNU, Intel) con el fin de evaluar las optimizaciones que generan para el hardware; y dos bibliotecas de álgebra lineal (OpenBLAS, Intel MKL) para medir su influencia en el tiempo de cómputo. Este primer análisis pretende ser un punto de referencia para la evaluación y comparación de futuras versiones del código, como así también para el caso de actualizaciones de software y/o hardware en los clústeres.Publicado en: Mecánica Computacional vol. XXXV, no. 11Facultad de Ingenierí