EE - Artigos Publicados em Periódicos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/513
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6 resultados
Resultados da Pesquisa
- ItemSimulação numérica da ação de ondas sobre um dispositivo de captação de energias das ondas do tipo coluna de água oscilante(2011) Davyt, Djavan Perez; Teixeira, Paulo Roberto de Freitas; Ramalhais, Rúben dos Santos; Didier, Eric LionelNeste trabalho é analisado um dispositivo de extração de energia das ondas do tipo coluna de água oscilante sob a ação de ondas regulares de diferentes períodos. São realizadas variações no comprimento submerso da parede frontal e no comprimento da câmara. Para tal é utilizado o código numérico FLUINCO, o qual é baseado nas equações RANS e a discretização é realizada utilizando o método semi-implícito de Taylor-Galerkin de dois passos. Uma formulação lagrangeana-euleriana arbitrária (ALE) é utilizada para permitir a solução de problemas que envolvem movimentos da superfície livre. Alguns resultados são comparados com os obtidos utilizando o programa FLUENT. São apresentados a amplificação (relação entre a altura da onda incidente a e dentro da câmara), distribuição das velocidades e vetores de velocidade.
- ItemNumerical simulations of low reynolds number flows past elastically mounted cylinder(2012) Gonçalves, Rafael Almeida; Teixeira, Paulo Roberto de Freitas; Didier, Eric LionelThe vortex-induced vibration (VIV) phenomenon has drawn the attention of researchers in Engineering for several decades. An example is the riser used for petroleum exploration, in which it is subjected to marine flows that may cause oscillations due to vortex shedding. In this paper, numerical analyses of the phenomena that occur in the interaction among flows at low Reynolds numbers and elastically mounted cylinders are presented. The simulation is carried out by using the numerical model Ifeinco that uses a semi-implicit two-step Taylor-Galerkin method to discretize the Navier-Stokes equations and the arbitrary Lagrangean-Eulerian formulation to follow the cylinder motion. The rigid body motion description is calculated by using the Newmark method. Firstly, the characteristics of the vortex generation process for the fixed cylinder are analyzed. In this case, the Strouhal number, the mean drag and the RMS lift coefficients for Reynolds numbers ranging from 90 to 140 are shown. Afterwards, an analysis of a flexible supported cylinder (with a spring and a damper) in transverse direction subject to flows with Reynolds numbers ranging from 90 to 140 is carried out. The cylinder displacement and the vibration frequencies are studied; the synchronization between the vortex shedding and the vibration frequency (lock-in) is analyzed. Similar results to the experimental ones developed by Anagnostopoulos and Bearman (1992) were obtained in this study.
- ItemNumerical simulation of an oscillating water column device using a code based on Navier-Stokes equations(2013) Teixeira, Paulo Roberto de Freitas; Davyt, Djavan Perez; Didier, Eric Lionel; Ramalhais, Rúben dos SantosThe study of ways of converting ocean wave energy into a useful one and the improvement of the existing equipment are complex engineering problems and very important issues in today’s society. In this paper, the onshore oscillating water column device, in a 10 m deep channel subjected to 1 m high incident wave and wave periods from 4 s to 15 s, is investigated. The numerical analyses are carried out using Fluinco model that deals with incompressible flow problems based on the Navier-Stokes equations and employs the two-step semi-implicit Taylor-Galerkin method. An aerodynamic model is implemented in the algorithm to determine the air pressure that is imposed on the free surface. Analyses are divided into two sections. In the first section, the flow variables obtained by Fluinco and the commercial model Fluent are compared and similar results are obtained. In the second section, an investigation of the chamber geometry and turbine characteristic relation that provide the best device performance is carried out. In this case, variations in the front wall depth, the chamber length, the turbine characteristic relation and the chamber height, are made.
- ItemLinear static and dynamic analysis of thin laminated composite structures with a triangular finite element(2010) Isoldi, Liércio André; Awruch, Armando Miguel; Morsch, Inácio Benvegnu; Teixeira, Paulo Roberto de FreitasLinear static and dynamic behavior of thin laminate composite structures are analyzed in this study using the Finite Element Method (FEM). Triangular elements with three nodes and six degrees of freedom per node (three displacement and three rotation components) are used. For static analysis the equilibrium equations are solved using Pre-conditioned Gradient Conjugate Method (GCM) while the dynamic solution is performed using the classical Newmark Method. Analytical evaluation of consistent element mass matrix and determination of membrane and membrane-bending coupling element stiffness matrix in the explicit form are showed. Numerical examples are presented and compared with results obtained by other authors with different types of elements and different schemes, proving the validity and effectiveness of the developed model.
- ItemElastic and elasto-plastic buckling analysis of perforated steel plates(2013) Real, Mauro de Vasconcellos; Isoldi, Liércio André; Damas, Alexandra Pinto; Helbig, DanielMany steel structures such as ships and offshore structures are composed by welded stiffened or unstiffened plate elements. Cutouts are often provided in these plate elements for inspection, maintenance, and service purposes, and the size of these holes could be significant. In many situations, these plates are subjected to axial compressive forces which make them prone to instability or buckling. If the plate is slender, the buckling is elastic. However, if the plate is sturdy, it buckles in the plastic range causing the so-called inelastic (or elasto-plastic) buckling. Furthermore, the presence of these holes redistributes the membrane stresses in the plate and may cause significant reduction in its strength in addition to changing its buckling characteristics. So, the objective of this paper is to investigate the changes that the presence of circular holes produces in the elastic and inelastic buckling of steel rectangular plates. The finite element method (FEM) has been used to evaluate the elastic and elastoplastic buckling load of uniaxially loaded rectangular plates with circular cutouts. By varying the hole diameter, the plate aspect ratio and the plate thickness during the analyses, the changes in the plate buckling behavior can be determined. The results show that while the circular hole can in some cases even increase the elastic buckling load, the elasto-plastic buckling load is reduced by the presence of the cutout.
- ItemViabilidade de conversão da energia de correntes marinhas na plataforma continental Sul do Brasil(2012) Kirinus, Eduardo de Paula; Stringari, Caio Eadi; Marques, Wiliam CorreaVárias formas de conversão de energia foram desenvolvidas no decorrer dos anos, com destaque para os conversores de energia das correntes, que demonstram alta capacidade de geração energética e já se encontram em funcionamento em algumas regiões do mundo. A Plataforma Continental Sul do Brasil possui alta variabilidade espacial e temporal no regime de correntes costeiras, fato que dificulta a conversão unidirecional de energia. Neste sentido, para a conversão de energia das correntes, seria recomendado o uso de turbinas helicoidais que são capazes de gerar energia de forma multidirecional. A região de estudo demonstrou possuir duas regiões com ótimo potencial energético, onde na região mais viável a produção média de energia pode alcançar 40 MWh e ainda valores integrados de 13GWh/ano. Através da simulação de sítios de conversão nos locais de maior viabilidade, foi observado que o padrão da velocidade residual das correntes é predominantemente direcionado para sudoeste, devido à predominância de ventos de quadrante norte, sendo o sítio mais energético capaz de gerar 274 GWh durante os 280 dias de simulação. Foi observado que os ciclos de maior geração energética ocorrem com periodicidade de 16 dias demonstrando alta correlação com eventos associados à passagem de frentes meteorológicas na região.