Navegando por Assunto "Elementos finitos"

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Acesso aberto (Open Access)
An analysis of total phosphorus dispersion in lake used as a municipal water supply
(Academia Brasileira de Ciências, 2015-09) LIMA, Romulo Correa; MESQUITA, André Luiz Amarante; BLANCO, Claudio José Cavalcante; SANTOS, Maria de Lourdes Souza; SECRETAN, Yves
In Belém city is located the potable water supply system of its metropolitan area, which includes, in addition to this city, four more municipalities. In this water supply complex is the Água Preta lake, which serves as a reservoir for the water pumped from the Guamá river. Due to the great importance of this lake for this system, several works have been devoted to its study, from the monitoring of the quality of its waters to its hydrodynamic modeling. This paper presents the results obtained by computer simulation of the phosphorus dispersion within this reservoir by the numerical solution of two-dimensional equation of advection-diffusion-reaction by the method θ/SUPG. Comparing these results with data concentration of total phosphorus collected from November 2008 to October 2009 and from satellite photos show that the biggest polluters of the water of this lake are the domestic sewage dumps from the population living in its vicinity. The results obtained indicate the need for more information for more precise quantitative analysis. However, they show that the phosphorus brought by the Guamá river water is consumed in an area adjacent to the canal that carries this water into the lake. Phosphorus deposits in the lake bottom should be monitored to verify their behavior, thus preventing the quality of water maintained therein.
Acesso aberto (Open Access)
Análise numérica das distorções em soldas de topo do aço estrutural naval via elementos finitos
(Universidade Federal do Pará, 2024-12-12) MOTA, João Epifânio da; LAMEIRA, Pedro Igor Dias; http://lattes.cnpq.br/5391645898597252; https://orcid.org/0000-0001-8038-8276
In this research, one of the alternatives for evaluating welding distortions was to use computer simulation. A numerical analysis was then developed to determine the transverse distortion field in welded joints. The numerical simulations were carried out using commercial software, ANSYS Workbench, based on the Finite Element Method (FEM). Input parameters were entered, such as: current, voltage, welding speed and initial temperature of the virtual plate. The simulations used a virtual ASTM A36 steel plate welded using the Flux-Cored Arc Welding (FCAW) process. The influence of the geometry of the “V” and “U” bevel types on the thermal efficiency of welding, restrictions on plate distortions and heat input were verified. Although these initial simulations are qualitatively comparative, they have been validated on the basis of results from the literature, i.e. they are of quantitative importance. However, only specific results were verified that presented possibilities for combining butt joints and heat sources in structural steel. It was therefore essential to establish a sequential analysis method for adjusting the model, which would provide the main characteristics of a welding process (heat source, joint geometry, the thermodependent properties of A36 steel). The results of the analysis showed good approximation and agreement with the literature analyzed for both the temperature and deformation fields.
Acesso aberto (Open Access)
Análise termoelástica experimental e computacional por elementos finitos da parede externa em concreto armado de um forno de cozimento de anodo
(Universidade Federal do Pará, 2004-12-16) TEIXEIRA, Marcelo Rassy; SOUZA, Remo Magalhães de; http://lattes.cnpq.br/1995895693959225
This thesis presents a study about the behavior of a reinforced concrete structure subjected to high thermal variations. The structure under investigation is the external wall of an anode furnace used in Aluminum production, and is subjected to thermal variations in the range of 125C (2282 F) due to the furnace operation. The main motivations for the study were the presence of large deformations and occurrence of cracks in the structure, which could cause the furnace to become inoperable. The objective of the research was to investigate the causes of these structural pathologies, as well as to establish retrofit proposals for the structure. For this purpose, experimental and numerical studies were carried out. At first, the structure was monitored using displacement transducers and temperature sensors (thermocouples) connected to a data acquisition system, which could automatically obtain and store samples along the test period. Next, computer models were developed, using a multiphysics Finite Element Code called Algor, for the evaluation of temperature distribution and corresponding thermal stresses and strains in the structure. In these studies, stationary and transient heat conduction analyses were performed, followed by thermal stress analyses. As a conclusion of this research, it can be stated that the proposed methodology, based on advanced tools of structural engineering, was very suitable for the study of the presented phenomenon, since it rendered a precise and economic solution for the problem.
Acesso aberto (Open Access)
Modelagem numérica de dados MCSEM 2.5-D
(Universidade Federal do Pará, 2012-04-20) SILVA, Hilton Farias da; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
This work deals with the implementation of numerical 2.5-D Marine Controlled Source Electromagnetic (MCSEM) modeling applied to hydrocarbon exploration in stratified environment. In the mathematical formulation the fields were assumed to have two parts: the primary and the secondary ones. The first uses of Schelkunoff potentials in its formulation and they were employed in both (x; ky; z; !) and (x; y; z; !) domains. The secondary fields are solved in the frequency domain space (x; ky; z) by finite element method. With a Inverse Fourier transform, the secondary fields were taken in the domain (x; y; z). From the total field, we can show the influence of an oil reservoir in a stratified environment and its sensitivity to the lateral extension of a hydrocarbon reservoir.
Acesso aberto (Open Access)
Otimização computacional da técnica de elementos finitos para o modelamento geofísico eletromagnético
(Universidade Federal do Pará, 1991-11-25) BATISTA, Lurimar Smera; PORSANI, Milton José; http://lattes.cnpq.br/1428637808064409
Acesso aberto (Open Access)
Transporte de ozônio em hidrogerador de 311 mva: modelagem fluidodinâmica tridimensional de máquina elétrica dos elementos finitos. através do método
(Universidade Federal do Pará, 2024-02-29) GIROTTO, Gustavo Gaspar; OLIVEIRA, Rodrigo Melo e Silva de; http://lattes.cnpq.br/4768904697900863
In this work, a three-dimensional numerical model of fluid dynamics is developed for a single 311 MVA power generator unit in a hydroelectric power plant using the finite element method. The goal is to study the ozone transport mechanisms within the enclosed structure of the electrical generator machine. Ozone is produced by partial discharges related to some faults in the stationary bars. To analyze the ozone transport from localized sources, a three-dimensional fluid dynamics model of an operational hydrogenerator is developed and presented for the first time. The model has a high level of geometric details. Additionally, a new proposal to simplify the modeling of radiators is implemented and validated. The modeled structure is based on an electrical machine from the Campos Novos hydrogenerator and consists of 378 coil-type stationary bars made of mica-coated copper and, externally, by a layer of semiconductor coating. Other parts are also represented, including the stationary core and air deflectors made of stainless steel, copper radiators, the rotor with its epoxy surface, and the floor and external walls made of concrete. In the fluid dynamics model, a finite element mesh is designed to represent the air regions inside the hydrogenerator and the surfaces of materials reacting with ozone (with their respective reaction rates), where air flow and ozone transport are modeled using the Navier-Stokes equations and the law of mass conservation. Partial discharge sources are represented by ozone sources with prismatic shapes, positioned on the surfaces of stationary bars. Ozone concentrations are calculated inside and around the generator machine. The rotor radius is 3.8075 m, and its rotation frequency is 200 RPM. The radial air velocity due to interpolar ventilation is also considered (2.2 m/s, as experimentally verified on-site). The radial velocity near the radiators is 3 m/s. It is concluded that the ozone transport profile is influenced by the source position on the stationary bars, so determining the source location is possible and depends on determining the local and global maximum ozone concentration areas on the radiators.