MARCELO DA SILVA ROCHA

MARCELO DA SILVA ROCHA

(Fonte: Lattes)

Resumo

Possui graduação em Engenharia Civil pela Universidade Federal de Juiz de Fora (1996), mestrado em Engenharia Civil pela Universidade Estadual de Campinas (1998) e doutorado em Engenharia Mecânica pela Universidade de São Paulo (2005). Realizou estágio de pós-doutorado em Engenharia Mecânica na Universidade de São Paulo (2007) e em Engenharia Nuclear no Instituto de Pesquisas Energéticas e Nucleares (2009). Atualmente é Pesquisador Adjunto do Centro de Engenharia Nuclear (CEENG) do Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN). Atua como docente e pesquisador nas áreas de termohidráulica de reatores, energias renováveis, interação fluido-estrutura e aplicações de nanotecnologia. (Texto extraído do Currículo Lattes em 16 nov. 2021)

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Improving the RELAP5 code modeling of the siphon break effect in a pool type research reactor
2024 - BELCHIOR JUNIOR, ANTONIO; SOARES, HUMBERTO V.; FREITAS, ROBERTO L.; MESQUITA, ROBERTO N. de; ROCHA, MARCELO da S.; ANDRADE, DELVONEI A. de
The pool water of a research reactor is used for emergency cooling of the reactor core. Siphon breakers are installed in the lines of the Core Cooling System to stop the loss of water from the pool due to the siphon effect during an accident involving piping ruptures. Previous studies discuss the effectiveness of siphon breakers based on the air inlet area and question the ability of one-dimensional thermo-hydraulic codes to model the siphon break devices. By means of comparison with experimental results, this work demonstrates the ability of the RELAP5/MOD3.3 code to model the performance of the siphon breaker. There was satisfactory agreement between the numerical and experimental results, showing that, as the air intake areas of the siphons decrease, their effectiveness also decreases, resulting in greater drainage of the pool water. For smaller air intake areas, the RELAP5/MOD3.3 code showed conservative results, overestimating the reactor pool water losses.
The production of clean and low-cost hydrogen through nuclear power plants
2024 - MORAES, EDUARDO de; SILVA, ELECTO E.L. da; ROCHA, MARCELO S.
Numerical analysis of the Rectangular Natural Circulation Loop of IPEN/CNEN-SP in the Dymola software
2024 - CELESTINO, P.A.P.; ROCHA, M.S.
Numerical model for calculation of hydraulic transients with two‑phase flow and fluid-structure interaction
2024 - ROCHA, PEDRO H. do N.; CAMPOS, JOSIE A.A. de; CAMARGO, MICELLI R.; ROCHA, MARCELO da S.
Fluid transport systems such as pipelines are subject to loads whenever changes in fluid momentum or in pipeline structure occur. These loads can generate extremely harmful hydraulic transients which may be responsible for several major accidents. This paper presents a model for the solution of these hydraulic transients, considering two-phase flow and fluid–structure interaction. Mathematical and numerical solutions are proposed and analyzed for the proper capture of the physical phenomena associated with the fluid compressibility and fluid celerity, which are variable in two-phase fluid, together with the disturbances generated by the fluid–structure interaction. The proposed solution for the model considers the simultaneous action of these phenomena. The developed numerical model is based on the solution of the mathematical model formed by a system of four partial differential equations, in which the necessary adaptations are integrated in fluid–structural equations and in the nonlinear mathematical coefficients for the solution of the compressible and two-phase flow in question. Classical formulation is selected for the implementation of friction between fluid and pipe in the model. For the solution, it is applied the method of characteristics and finite difference, with subsequent numerical integration. The validation of the results is carried out based on comparisons with experimental and analytical data. The model presented, in general, was quite adherent to the experimental and analytical results, mainly in relation to the first pressure peak, which is one of the main focuses of the transient analyses.
CFD Simulation of isothermal upward two-phase flow in a vertical annulus using interfacial area transport equation
2023 - CERAVOLO, FLAVIO E.; ROCHA, MARCELO da S.; MESQUITA, ROBERTO N. de; ANDRADE, DELVONEI A. de
This work presents a numerical simulation of a vertical, upward, isothermal two-phase flow of air bubbles and water in an annular channel applying a Computational Fluid Dynamics (CFD) code. For this, the Two-Fluid model is applied considering interfacial force correlations, namely: drag, lift, wall lubrication, turbulent dispersion, and virtual mass. The turbulence k-ε model effects and the influence of One-group Interfacial Area Transport Equation (IATE) are taken into account, in this case, the influence of two source term correlations for the bubble breakup and coalescence IATE is analysed. The work assesses whether the code properly represents the physical phenomenon by comparing the simulation results with experimental data obtained from the literature. Six flow conditions are evaluated based on two superficial liquid velocities and three void fractions in the bubbly flow regimen. The annular channel adopted has an outer pipe with an internal diameter of 38.1 mm and an inner cylinder of 19.1 mm. To represent this geometry, a three-dimensional mesh was generated with 160,000 elements, after a mesh sensitivity study. The void fraction distribution, taken radially to the flow section, is the main parameter analysed as well as interfacial area concentration, interfacial gas velocity, and bubble sizes distribution. The CFD model implemented in this work demonstrates satisfactory agreement with the reference experimental data but indicates the need for further improvement in the phase interaction models.
Development of an open source tool for water hammer and fluid-structure interaction simulation in nuclear reactors systems
2022 - ROCHA, MARCELO da S.; ANDRADE, DELVONEI A. de
Estudo teórico e experimental das propriedades termofísicas do óxido de grafeno
2022 - SANTOS, GABRIEL O.; ROCHA, MARCELO da S.
CFD simulation of isothermal upward two-phase flow in a vertical tube of annular section
2020 - CERAVOLO, FLÁVIO E.; ROCHA, MARCELO da S.; ANDRADE, DELVONEI
This work presents a simulation of a vertical, upward, isothermal two-phase flow of air bubbles and water in an annular channel applying a Computational Fluid Dynamics (CFD) code. The simulation considers an Eulerian frame, with a two-fluid model, specific correlations for turbulence modeling, and bubble-induced turbulence effects. The work intends to assess the accuracy of the code by comparing the simulation results with experimental data obtained from the literature. The annular channel has an equivalent hydraulic diameter of 19.1 mm, where the outer pipe has an internal diameter of 38.1 mm, the inner cylinder 19.1 mm, and a total length of 1900 mm. The void fraction distribution, taken radially to the flow section, is the main parameter analyzed besides interfacial area concentration (IAC), interfacial gas velocity, and bubble diameters distribution. The numerical models applied in this work demonstrate satisfactory agreement with the experimental data but indicate the need for further improvement in the phase interaction models.
Investigation on the improvement of thermal properties of TiO2 nanofluids
2020 - ROCHA, M.d.; ANDRADE, D.A.; MOREIRA, P.G.; STEFANIAK, I.; MARTINS, J.G.
This work aims to investigate the thermophysical properties of TiO2 nanofluids in the water base experimentally and also comparing results with existing literature data and theoretical models. Studies reveal that nanofluids present increasing in thermal conductivity and other important properties related to the heat transfer capacity compared to the base fluid. In this way, it can be classified as promising fluids for heat transport applications. As the proposal is to use it in high thermal flux systems, the survey of experimental measurements was performed to verify whose of the main parameters have more influence over such properties. Thermal conductivity, viscosity, surface contact angle and some visualization of nanoparticles in SEM were carried out in order to understand the nanofluids properties modifications. The TiO2 nanofluids in water base solutions were prepared for this study using the ultrasonic dispersion technique for three distinct volume concentrations: 0.1%, 0.01%, and 0.001%. Samples were initially prepared using an ultrasonic disrupter to make a homogeneous solution. This is an important step in sample analyses concerning the homogeneity influence on thermal conductivity measurements. With all samples prepared, some steps were followed to ensure the dispersion of nanoparticles and thus obtaining more accurate results Nanofluids samples were visualized in a scanning electron microscope (SEM) JEOL, model JSM 6701F at IPEN. Figure 2 shows the TiO2 nanoparticle's image observed. Preliminary tests for determining the thermophysical properties of nanofluids were: density, thermal conductivity, viscosity and surface contact angle. Concentration and temperature effects were investigated in preliminary tests for measurement of the thermal conductivity of nanofluids: this step consists of measuring the thermal conductivities and viscosities of nanofluids for all concentrations (0.001%, 0.01% and 0.1% vol.) at 15°C, 25oC and 35oC. ASTM D5334-08 (2008) describes the standard procedure for determining thermophysical properties and is based on the classical Linear Probe Method also known as the Transient Hot-Wire Method.
Computer simulator for the research reactor IPEN/MB-01
2020 - CASORLA, M.; BITELLI, U.D.; ANDRADE, D.A.; ROCHA, M.S.
A computer simulator for the Nuclear Research Reactor IPEN / MB-01 was developed to be a tool for teaching, training, and recycling professionals. The simulator was developed on a SCADA platform (Supervision and Data Acquisition System) with support calculation software, where mathematical models, and graphical interface configurations form a friendly platform, which allows the trainee to be identified with the physical systems of the research reactor. Simplified modeling of the main physical phenomena related to the operation of the reactor, and the reactivity control systems, reactor cooling and reactor protection was used. The Simulator allows an HMI (Human-Machine Interaction) by manipulating system variables and monitoring trends in quantities during the operation of the reactor, showing an interactive tool for teaching, training and recycling for professionals in the Nuclear Reactor IPEN / MB -01, allowing simulations of the start, power and stop operations.