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Search Results: 1 - 10 of 61260 matches for " Aristeu da Silveira-Neto "
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Rotational Oscillation Effect on Flow Characteristics of a Circular Cylinder at Low Reynolds Number  [PDF]
Alice Rosa da Silva, Aristeu da Silveira-Neto, Ant?nio Marcos Gon?alves de Lima
World Journal of Mechanics (WJM) , 2015, DOI: 10.4236/wjm.2015.510019
Abstract: Two dimensional numerical simulations of flow around a rotationally oscillating circular cylinder were performed at Re = 1000. A wide range of forcing frequencies, fr, and three values of oscillation amplitudes, A, are considered. Different vortex shedding modes are observed for a fixed A at several values of fr, as well as for a fixed fr at different values of A. The 2C mode of vortex shedding was obtained in the present study. It is important to point out that this mode has not been observed by other investigators for rotationally oscillating case. Also, it is verified that this mechanism has great influence on the drag coefficient for high frequency values. Furthermore, the lift and pressure coefficients and the power spectra density are also analyzed.
Theoretical Study of Fully Developed Turbulent Flow in a Channel, Using Prandtl’s Mixing Length Model  [PDF]
Luigi A. Antonialli, Aristeu Silveira-Neto
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.64061
Abstract: This research used the common decomposition of the velocity and pressure in an average part and a fluctuating part, for high Reynolds number, of the Navier-Stokes equation, which leads to the classic problem of turbulent closure. The Prandtl’s mixing length model, based on the Boussinesq hypothesis and traditionally used for free shear flows, was chosen and adapted for internal flows to solve the closure problem. For channel flows, Johann Nikuradse proposed a model for the Prandtl mixing length. In the present paper, which has an academic character, the authors made a return to the model of the mixing length of Prandtl and the model of Nikuradse, to solve turbulent flows inside a plane channel. It was possible to develop an ordinary differential model for the velocity in the direction of the flow whose solution occurs computationally in a simple but extremely accurate way when compared with Direct Numerical Simulation databases. For the viscous stress on the wall, it was possible to determine the exact mathematical solution of the ordinary differential equation. It is a model of great academic value and even to be used as reference for verification of computational codes destined to the solution of complete numerical and computational models.
Numerical simulations of flows over a rotating circular cylinder using the immersed boundary method
Silva, Alice Rosa da;Silveira Neto, Aristeu da;Lima, Antonio Marcos G. de;Rade, Domingos Alves;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2011, DOI: 10.1590/S1678-58782011000100014
Abstract: in this paper, numerical simulations of incompressible flows around rotating circular cylinders have been performed. the two-dimensional navier-stokes equations are solved by using a cartesian non-uniform grid. the immersed boundary method (ibm) with the virtual physical model (vpm) was used in order to model the presence of the circular cylinder in the flow. the fractional time step method was used to coupling the pressure and velocity fields. the simulations were carried out for reynolds numbers equals to 60, 100 and 200 for different specific rotations. the effects of rotation on flow characteristics and fluctuating forces were investigated. the strouhal number, obtained by performing the fast fourier transform (fft) of the temporal distribution of the lift coefficient, and the pressure coefficients, were also been calculated. vorticity contours are presented considering different values of the reynolds number and specific rotation. the numerical results obtained are compared to those obtained by other authors and the usefulness of the numerical methodology composed by the combination of the ibm with the vpm to simulate flows in the presence of mobile bodies is highlighted.
Numerical simulation of two-dimensional complex flows around bluff bodies using the immersed boundary method
Silva, Ana Lúcia F. de Lima e;Silva, Alice Rosa da;Silveira Neto, Aristeu da;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2007, DOI: 10.1590/S1678-58782007000400006
Abstract: this paper presents a two-dimensional numerical simulation of flows around different bluff bodies, at re = 100 and 200, using the immersed boundary (ib) method, as a sequence of a previous work. the force density term required by the ib method is obtained with the virtual physical model (vpm). simulations were carried out for two circular cylinders of different diameter in tandem, two cylinders of the same diameter in tandem and two cylinders placed in side by side arrangement. the configurations of seven cylinders in a 'v' arrangement, for angles of 40o < a < 180o, were also simulated. a configuration of 23 different bluff bodies, representing a transverse cut in a central tower of an offshore structure, has been also simulated and the results were compared with a single compact square, of equivalent size. the strouhal number, the drag and the lift coefficients were also calculated. the strouhal number is calculated using the fast fourier transform (fft) of the lift coefficient temporal distribution. visualization of the vorticity and pressure fields and the streamlines are presented for each simulation showing the flow dynamics and patterns. it was possible to verify that the ib method with vpm is a powerful methodology to simulate flows in the presence of complex geometries.
Computations of the flow past a still sphere at moderate reynolds numbers using an immersed boundary method
Campregher, Rubens;Militzer, Julio;Mansur, Sérgio Said;Silveira Neto, Aristeu da;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2009, DOI: 10.1590/S1678-58782009000400009
Abstract: this paper presents an immersed boundary formulation for three-dimensional incompressible flows that uses the momentum equation to calculate the lagrangian force field indirectly imposing the no-slip condition on solid interfaces. in order to test the performance of this methodology the flow past a sphere for reynolds numbers up to 1,000 have been calculated. results are compared with numerical data from other authors and empirical correlations available in the literature. the agreement is found to be very good.
Aspectos estratégicos do modelo de gest?o em incubadoras de empresas de base tecnológica
Zouain, Deborah Moraes;Silveira, Aristeu Coelho da;
Cadernos EBAPE.BR , 2006, DOI: 10.1590/S1679-39512006000300009
Abstract: the study is based on strategic administration, focusing on incubators of technology-based companies, namely support undertakings for the spawning and development of such kind of companies. it stresses the importance over the past few years of the movement of incubators in brazil and underscores the need, on the part of incubators, to adopt management models that are more relevant to the brazilian reality. for this purpose, research was conducted into the dominant model in incubator management, as well as a comparison with the conceptual model described in existing literature. the research was of an explanatory nature making use of bibliographical, documentary and field sources. the criteria of accessibility and existing structure of two incubators (ufrj and puc/rj) determined the sample. the results show how more adequate models provide better conditions for the success of this type of undertaking
Síndrome de Kleine-Levin relato de um caso
Silveira Neto, Octávio da;Silveira, Octávio Augusto da;
Arquivos de Neuro-Psiquiatria , 1991, DOI: 10.1590/S0004-282X1991000300017
Abstract: a case of a 14 year-old boy suffering from kleine-levin syndrome is described. the diagnosis was made by symptoms which suggested this disorder: megaphagia, hi-persomnia and hipersexuality. a brief review is made emphasizing the pathophysiology, diagnosis and treatment of this syndrome which is frequently misdiagnosed.
A quest?o da tecnologia na rela??o trabalho-educa??o: das concep??es aos argumentos e às formula??es legais
Lobo Neto, Francisco José da Silveira;
Trabalho, Educa??o e Saúde , 2009, DOI: 10.1590/S1981-77462009000400005
Abstract: from the speeches regarding technology found in the most comprehensive lines about professional education, it is intended to bring understanding elements of the normative formulations within the scenario of the current national education bases and guidelines law (law n.o 9.394, as of december 20, 1996). then it is carried out the speeches analysis regarding technology articulated on a 'technology' of the professional education discussion and proposition speeches and their repercussion in the legal formulation, from bill n.o 1.258/88 up to the resulting final writing that comprises law n.o 9.394, as of december 20, 1996. in conclusion, it is considered the research perspective, of reflexive debate, to build proposals that take into account the professional education as human education and as transforming praxis of the work-technology-profession-education relationships, in the concrete specificity of every situation and within the set of situations. a redemption perspective of the professional education as a fully public policy, aimed at the interests of the majority, the working class.
Técnicas de Anima o em Ambientes Tridimensionais
Walter Dutra da Silveira Neto,Adrei Krepsky
Revista Eletr?nica de Sistemas de Informa??o , 2005,
Abstract: Este artigo faz um estudo dos princípios fundamentais de anima o desenvolvidos na década de trinta aplicados no ambiente de anima o tridimensional contemporanea. Tais princípios foram identificados e um software de anima o tridimensional foi escolhido. Foram desenvolvidos um ambiente e um contexto para anima o. Os princípios foram testados e verificou-se uma aplicabilidade satisfatória devido à versatilidade do software.
Resenha de "Matrizes da modernidade republicana: cultura política e pensamento educacional no Brasil" de Marlos Bessa Mendes Rocha
Francisco José da Neto Silveira Lobo
Revista Brasileira de Educa??o , 2004,
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