Jhon Goulart - Academia.edu (original) (raw)

Papers by Jhon Goulart

Uncertainty Modeling: Fundamental Concepts and Models

This chapter presents an overview of computational models and formulations, a description of some... more This chapter presents an overview of computational models and formulations, a description of some error estimators in Boundary Element Methods (BEM) and in Finite Element Methods (FEM), and some perspectives of the use of these error estimators in Bayesian approaches for Model Validation.

O presente estudo consiste na avaliacao numerica de um arranjo formado por quatro cilindros subme... more O presente estudo consiste na avaliacao numerica de um arranjo formado por quatro cilindros submetidos a um escoamento transiente, bidimensional, incompressivel, laminar e com conveccao forcada. A avaliacao geometrica e realizada atraves do metodo Design Construtal. O problema possui uma restricao dada pela soma da area dos cilindros e tres graus de liberdade: ST1/D (razao entre o passo transversal dos cilindros frontais e o diâmetro dos cilindros), ST2/D (razao entre o passo transversal dos cilindros posteriores e o diâmetro dos cilindros) e SL/D (razao entre o passo longitudinal dos cilindros frontais e posteriores e o diâmetro dos cilindros). Para todas as simulacoes sao considerados numeros de Reynolds e Prandtl constantes, ReD = 100 e Pr = 0.71. As equacoes de conservacao de massa, quantidade de movimento e energia sao resolvidas atraves do Metodo dos Volumes Finitos (FVM). O principal objetivo e avaliar o efeito dos graus de liberdade sobre o coeficiente de arrasto (C D) e o n...

O presente estudo consiste na avaliacao numerica de um arranjo triangular de corpos rombudos subm... more O presente estudo consiste na avaliacao numerica de um arranjo triangular de corpos rombudos submetidos a um escoamento transiente, bidimensional, incompressivel, laminar e com conveccao forcada. A avaliacao geometrica e realizada atraves do metodo Design Construtal. O problema possui uma restricao dada pela soma da area dos corpos rombudos e dois graus de liberdade: ST/D (razao da distância entre o centro dos corpos rombudos posteriores e a dimensao de suas arestas), SL/D (razao da distância longitudinal entre os centros dos corpos rombudos, frontal e posteriores, e a dimensao de suas arestas). Para todas as simulacoes sao considerados numeros de Reynolds e Prandtl constantes, ReD=100 e Pr = 0.71. As equacoes de conservacao de massa, quantidade de movimento e energia sao resolvidas atraves do Metodo dos Volumes Finitos (FVM). O principal objetivo e avaliar o efeito dos graus de liberdade sobre o coeficiente de arrasto (CD) e o numero de Nusselt (NuD) entre os corpos rombudos e o es...

Defect and Diffusion Forum, 2017

The purpose of this work is to present a numerical study of a two-dimensional channel with two tr... more The purpose of this work is to present a numerical study of a two-dimensional channel with two triangular fins submitted to a laminar flow with forced convection heat transfer, evaluating the geometry of the first fin through the Constructal Design method. The main objectives are to maximize the heat transfer rate and minimize the pressure difference between the inlet and outlet flow of the channel for different dimensions of the first channel fin, considering the same Reynolds (ReH = 100) and Prandtl numbers (Pr = 0.71). The problem is subjected to three constraints given by the channel area, fin area and maximum occupancy area of each fin. The system has three degrees of freedom. The first is given by the ratio between height and length of the channel, which is kept fixed, H/L = 0.0625. The other two are the ratio between height and width of the upstream fin base (H3/L3) positioned on the lower surface of the channel, and the ratio between height and width of the downstream fin (H4/L4) positioned on the upper surface of the channel, which is also kept fixed, H4/L4 = 1.11. The problem is simulated for three different values of the fraction area of upstream fin (φ1 = 0.1, 0.2 and 0.3). For the numerical approach of the problem, the conservation equations of mass, momentum and energy are solved using the finite volume method (MVF). The results showed that a ratio of φ1 = 0.2 is the one that best meets the proposed multi-objective. It was also observed that φ1 = 0.1 led to a better fluid dynamics performance with a ratio between the best and the worst performance for fluid dynamics case of 25.2 times. For φ1 = 0.3, the best thermal performance is achieved, where the optimal case has a performance 65.75% higher than that reached for the worst case.

Defect and Diffusion Forum, 2017

The present study consists in a numerical evaluation of an arrangement formed by four cylinders s... more The present study consists in a numerical evaluation of an arrangement formed by four cylinders submitted to an unsteady, two-dimensional, incompressible, laminar and forced convective flow. The geometric evaluation is performed through the Constructal Design method. The problem has two restrictions given by the sum of the area of the cylinders and one occupation area and has three degrees of freedom: ST1/D (the ratio between the transverse pitch of the frontal cylinders and the diameter of the cylinders), ST2/D (the ratio between the transverse pitch of the posterior cylinders and the diameter of the cylinders) and SL/D (ratio between the longitudinal pitch of the frontal and posterior cylinders and the diameter of the cylinders). For all simulations the Reynolds number is kept constant, ReD = 100, and two different Prandtl numbers of Pr = 0.71 and 5.83 are considered, which simulates respectively the use of air and water as a fluid. The conservation equations of mass, momentum and energy are solved with the Finite Volume Method (FVM). The main objective is to evaluate the effect of the degrees of freedom on the drag coefficient (CD) and the Nusselt number (NuD) between the cylinders and the surrounding flow, as well as the optimal ST2/D values for three ratios of ST1/D = 1.5, 3.0 and 4.0, these results being obtained for ratios of SL/D = 1.5 and 4.0. Results showed that the ratio changes of ST1/D and ST2/D have a great influence on the drag coefficients and on the Nusselt number of the arrangement formed by the four cylinders, as well as on the geometries leading to the best fluid dynamics and thermal performance.

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Fluids

Isothermal turbulent flow around circular cylinders arranged side-by-side was numerically simulat... more Isothermal turbulent flow around circular cylinders arranged side-by-side was numerically simulated on a commercial finite-volumes platform, ANSYS® CFX, version 2020 R2. The turbulence was modeled by using k-ω shear stress transport (k-ω SST). Three different Reynolds numbers were computed, Red = 200, 1000, and 3000, which were based on the cylinder diameter, d, the free stream velocity, U∞, and the kinematic viscosity of the fluid, ν. Sided cylinders were spaced apart from each other, forming a p/d ratio equal to 2, which was kept constant throughout the computations regardless of changes in the Reynolds number. The drag coefficient, Cd, as well as its time traces, was evaluated along with the different wake topologies experienced by the cylinders (wide wake WW and narrow wake NW). The simulations were able to predict the bistable flow over the cylinders and the Cd changes associated with the wakes. Whenever a new wake topology was identified, the shape drag changed in accordance w...

Metals

Nodular cast iron has been commonly applied in industry and many engineering applications due to ... more Nodular cast iron has been commonly applied in industry and many engineering applications due to its low production cost and the similarity of its mechanical properties to carbon steel. The mechanical properties of nodular cast iron are very dependent on its microstructure and also on the characteristics of the graphite nodules. In this sense, the main objective of this paper was to evaluate and characterize the nodular cast iron grades GGG40, GGG60 and GGG70 in the absence of heat treatment. In addition, specimens were obtained from casted bars and blocks without the Y-block casting process. The microstructure was analyzed by optical microscopy with the support of computational image analysis for determination of the attributes of the graphite nodules and the quantification of each phase present in the microstructure of the nodular cast iron. The results showed that the microstructure has a strong effect on the material’s strength, especially the density of graphite nodules in the ...

Revista Interdisciplinar de Pesquisa em Engenharia, Dec 31, 2020

This paper aims to apply continuous wavelet transform - CWT - in the analysis of the transient si... more This paper aims to apply continuous wavelet transform - CWT - in the analysis of the transient signals with and without intermittency. For that evaluation, time-frequency analysis techniques were employed for two didactic signals and a experimental signal from velocity fluctuation. Thye velocity signal was acquired by a single hot wire probe. In all cases, the wavelet transform was able to identify periods with low energy levels, showing to be efficient in the identification of intermittency or anomalies in the signals.

Este trabalho simula numericamente a perda de carga e o coeficiente de atrito medio em canais com... more Este trabalho simula numericamente a perda de carga e o coeficiente de atrito medio em canais compostos utilizando o pacote ANSYS ® CFX. Foram avaliados 03 tipos de canais retangulares de altura H e largura W com um canal secundario ao longo de uma das paredes laterais. As dimensoes do canal secundario sao sua profundidade P e largura D. As simulacoes foram feitas para um escoamento laminar e incompressivel para uma faixa de Reynolds de 200 a 1200, baseado no diâmetro-hidraulico, D H , na velocidade media do canal, U m , e na viscosidade cinematica do fluido, ν. Os resultados mostraram que o coeficiente medio de atrito e funcao de um fator de forma C e inversamente proporcional ao numero de Reynolds. A utilizacao do diâmetro-hidraulico como escala de comprimento para o calculo do fator medio de atrito levou a uma dispersao dos resultados que foram melhor aproximados utilizando raiz quadrada da area da secao transversal do canal, . Solucoes transientes tambem foram avaliadas para ob...

Experimental technique was applied to evaluate the thermal field in a smooth flat plate under for... more Experimental technique was applied to evaluate the thermal field in a smooth flat plate under forced convection. The technique consists in capture the thermal image over different substrates built from different materials and peculiarities. Each substrate was heated by a constant heat source controlled by a power suplly Minipa and the thermal image was captured by a Thermal Camera Fluke™ Ti 125placed 120 mm from the heated pieces. The heated piece was inserted inside an aerodynamic channel whose the free stream velocity U¥ was controlled by a frequency inverter, and therefore, changing the Reynolds number. The experiments were run under ReL up to 6´ 104. The Reynolds number is based on the free stream velocity, the plate length and the kinematic viscosity of the fluid,n. The Prandlt number, based on the molecular diffusion and heat diffusion, n / a - ratio was computed to be 0.70. The outcomes obtained in the experimental campaign successfully described the local Nusselt number as ...

Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering, 2020

International Journal of Mechanical and Materials Engineering, 2020

This work aims for a novel thermoelastic analysis methodology based on experimental steady-state ... more This work aims for a novel thermoelastic analysis methodology based on experimental steady-state temperature data and numerical displacement evaluation. The temperature data was acquired using thermal imaging and used as the input for a boundary element method (BEM) routine to evaluate its consequent thermoelastic displacement. The thermoelastic contribution to the resultant displacement arises in the BEM formulation as a domain integral, which compromises the main benefits of the BEM. To avoid the necessity of domain discretization, the radial integration method (RIM) was applied to convert the thermoelastic domain integral into an equivalent boundary integral. Due to its mathematical development, the resultant formulation from RIM requires the temperature difference to be input as a function. The efficacy of the proposed methodology was verified based on experimental displacement fields obtained via digital image correlation (DIC) analysis. For this purpose, a CNC (computer numeri...

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

Gold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late... more Gold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late TTG event at the core of calderas, producing small porphyries and gold-rich VMS deposits; (2) a sanukitoïd event, producing alkaline and felsic subvolcanic plutons with large gold hydrothermal systems, and (3) a hydrothermal/structural event. A large part of the gold mineralization may be directly related to the unique geodynamic situation, including the first subduction with two generations of gold-enriched intrusions.

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

17th Brazilian Congress of Thermal Sciences and Engineering, 2018

Uncertainty Modeling: Fundamental Concepts and Models

This chapter presents an overview of computational models and formulations, a description of some... more This chapter presents an overview of computational models and formulations, a description of some error estimators in Boundary Element Methods (BEM) and in Finite Element Methods (FEM), and some perspectives of the use of these error estimators in Bayesian approaches for Model Validation.

O presente estudo consiste na avaliacao numerica de um arranjo formado por quatro cilindros subme... more O presente estudo consiste na avaliacao numerica de um arranjo formado por quatro cilindros submetidos a um escoamento transiente, bidimensional, incompressivel, laminar e com conveccao forcada. A avaliacao geometrica e realizada atraves do metodo Design Construtal. O problema possui uma restricao dada pela soma da area dos cilindros e tres graus de liberdade: ST1/D (razao entre o passo transversal dos cilindros frontais e o diâmetro dos cilindros), ST2/D (razao entre o passo transversal dos cilindros posteriores e o diâmetro dos cilindros) e SL/D (razao entre o passo longitudinal dos cilindros frontais e posteriores e o diâmetro dos cilindros). Para todas as simulacoes sao considerados numeros de Reynolds e Prandtl constantes, ReD = 100 e Pr = 0.71. As equacoes de conservacao de massa, quantidade de movimento e energia sao resolvidas atraves do Metodo dos Volumes Finitos (FVM). O principal objetivo e avaliar o efeito dos graus de liberdade sobre o coeficiente de arrasto (C D) e o n...

O presente estudo consiste na avaliacao numerica de um arranjo triangular de corpos rombudos subm... more O presente estudo consiste na avaliacao numerica de um arranjo triangular de corpos rombudos submetidos a um escoamento transiente, bidimensional, incompressivel, laminar e com conveccao forcada. A avaliacao geometrica e realizada atraves do metodo Design Construtal. O problema possui uma restricao dada pela soma da area dos corpos rombudos e dois graus de liberdade: ST/D (razao da distância entre o centro dos corpos rombudos posteriores e a dimensao de suas arestas), SL/D (razao da distância longitudinal entre os centros dos corpos rombudos, frontal e posteriores, e a dimensao de suas arestas). Para todas as simulacoes sao considerados numeros de Reynolds e Prandtl constantes, ReD=100 e Pr = 0.71. As equacoes de conservacao de massa, quantidade de movimento e energia sao resolvidas atraves do Metodo dos Volumes Finitos (FVM). O principal objetivo e avaliar o efeito dos graus de liberdade sobre o coeficiente de arrasto (CD) e o numero de Nusselt (NuD) entre os corpos rombudos e o es...

Defect and Diffusion Forum, 2017

The purpose of this work is to present a numerical study of a two-dimensional channel with two tr... more The purpose of this work is to present a numerical study of a two-dimensional channel with two triangular fins submitted to a laminar flow with forced convection heat transfer, evaluating the geometry of the first fin through the Constructal Design method. The main objectives are to maximize the heat transfer rate and minimize the pressure difference between the inlet and outlet flow of the channel for different dimensions of the first channel fin, considering the same Reynolds (ReH = 100) and Prandtl numbers (Pr = 0.71). The problem is subjected to three constraints given by the channel area, fin area and maximum occupancy area of each fin. The system has three degrees of freedom. The first is given by the ratio between height and length of the channel, which is kept fixed, H/L = 0.0625. The other two are the ratio between height and width of the upstream fin base (H3/L3) positioned on the lower surface of the channel, and the ratio between height and width of the downstream fin (H4/L4) positioned on the upper surface of the channel, which is also kept fixed, H4/L4 = 1.11. The problem is simulated for three different values of the fraction area of upstream fin (φ1 = 0.1, 0.2 and 0.3). For the numerical approach of the problem, the conservation equations of mass, momentum and energy are solved using the finite volume method (MVF). The results showed that a ratio of φ1 = 0.2 is the one that best meets the proposed multi-objective. It was also observed that φ1 = 0.1 led to a better fluid dynamics performance with a ratio between the best and the worst performance for fluid dynamics case of 25.2 times. For φ1 = 0.3, the best thermal performance is achieved, where the optimal case has a performance 65.75% higher than that reached for the worst case.

Defect and Diffusion Forum, 2017

The present study consists in a numerical evaluation of an arrangement formed by four cylinders s... more The present study consists in a numerical evaluation of an arrangement formed by four cylinders submitted to an unsteady, two-dimensional, incompressible, laminar and forced convective flow. The geometric evaluation is performed through the Constructal Design method. The problem has two restrictions given by the sum of the area of the cylinders and one occupation area and has three degrees of freedom: ST1/D (the ratio between the transverse pitch of the frontal cylinders and the diameter of the cylinders), ST2/D (the ratio between the transverse pitch of the posterior cylinders and the diameter of the cylinders) and SL/D (ratio between the longitudinal pitch of the frontal and posterior cylinders and the diameter of the cylinders). For all simulations the Reynolds number is kept constant, ReD = 100, and two different Prandtl numbers of Pr = 0.71 and 5.83 are considered, which simulates respectively the use of air and water as a fluid. The conservation equations of mass, momentum and energy are solved with the Finite Volume Method (FVM). The main objective is to evaluate the effect of the degrees of freedom on the drag coefficient (CD) and the Nusselt number (NuD) between the cylinders and the surrounding flow, as well as the optimal ST2/D values for three ratios of ST1/D = 1.5, 3.0 and 4.0, these results being obtained for ratios of SL/D = 1.5 and 4.0. Results showed that the ratio changes of ST1/D and ST2/D have a great influence on the drag coefficients and on the Nusselt number of the arrangement formed by the four cylinders, as well as on the geometries leading to the best fluid dynamics and thermal performance.

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Fluids

Isothermal turbulent flow around circular cylinders arranged side-by-side was numerically simulat... more Isothermal turbulent flow around circular cylinders arranged side-by-side was numerically simulated on a commercial finite-volumes platform, ANSYS® CFX, version 2020 R2. The turbulence was modeled by using k-ω shear stress transport (k-ω SST). Three different Reynolds numbers were computed, Red = 200, 1000, and 3000, which were based on the cylinder diameter, d, the free stream velocity, U∞, and the kinematic viscosity of the fluid, ν. Sided cylinders were spaced apart from each other, forming a p/d ratio equal to 2, which was kept constant throughout the computations regardless of changes in the Reynolds number. The drag coefficient, Cd, as well as its time traces, was evaluated along with the different wake topologies experienced by the cylinders (wide wake WW and narrow wake NW). The simulations were able to predict the bistable flow over the cylinders and the Cd changes associated with the wakes. Whenever a new wake topology was identified, the shape drag changed in accordance w...

Metals

Nodular cast iron has been commonly applied in industry and many engineering applications due to ... more Nodular cast iron has been commonly applied in industry and many engineering applications due to its low production cost and the similarity of its mechanical properties to carbon steel. The mechanical properties of nodular cast iron are very dependent on its microstructure and also on the characteristics of the graphite nodules. In this sense, the main objective of this paper was to evaluate and characterize the nodular cast iron grades GGG40, GGG60 and GGG70 in the absence of heat treatment. In addition, specimens were obtained from casted bars and blocks without the Y-block casting process. The microstructure was analyzed by optical microscopy with the support of computational image analysis for determination of the attributes of the graphite nodules and the quantification of each phase present in the microstructure of the nodular cast iron. The results showed that the microstructure has a strong effect on the material’s strength, especially the density of graphite nodules in the ...

Revista Interdisciplinar de Pesquisa em Engenharia, Dec 31, 2020

This paper aims to apply continuous wavelet transform - CWT - in the analysis of the transient si... more This paper aims to apply continuous wavelet transform - CWT - in the analysis of the transient signals with and without intermittency. For that evaluation, time-frequency analysis techniques were employed for two didactic signals and a experimental signal from velocity fluctuation. Thye velocity signal was acquired by a single hot wire probe. In all cases, the wavelet transform was able to identify periods with low energy levels, showing to be efficient in the identification of intermittency or anomalies in the signals.

Este trabalho simula numericamente a perda de carga e o coeficiente de atrito medio em canais com... more Este trabalho simula numericamente a perda de carga e o coeficiente de atrito medio em canais compostos utilizando o pacote ANSYS ® CFX. Foram avaliados 03 tipos de canais retangulares de altura H e largura W com um canal secundario ao longo de uma das paredes laterais. As dimensoes do canal secundario sao sua profundidade P e largura D. As simulacoes foram feitas para um escoamento laminar e incompressivel para uma faixa de Reynolds de 200 a 1200, baseado no diâmetro-hidraulico, D H , na velocidade media do canal, U m , e na viscosidade cinematica do fluido, ν. Os resultados mostraram que o coeficiente medio de atrito e funcao de um fator de forma C e inversamente proporcional ao numero de Reynolds. A utilizacao do diâmetro-hidraulico como escala de comprimento para o calculo do fator medio de atrito levou a uma dispersao dos resultados que foram melhor aproximados utilizando raiz quadrada da area da secao transversal do canal, . Solucoes transientes tambem foram avaliadas para ob...

Experimental technique was applied to evaluate the thermal field in a smooth flat plate under for... more Experimental technique was applied to evaluate the thermal field in a smooth flat plate under forced convection. The technique consists in capture the thermal image over different substrates built from different materials and peculiarities. Each substrate was heated by a constant heat source controlled by a power suplly Minipa and the thermal image was captured by a Thermal Camera Fluke™ Ti 125placed 120 mm from the heated pieces. The heated piece was inserted inside an aerodynamic channel whose the free stream velocity U¥ was controlled by a frequency inverter, and therefore, changing the Reynolds number. The experiments were run under ReL up to 6´ 104. The Reynolds number is based on the free stream velocity, the plate length and the kinematic viscosity of the fluid,n. The Prandlt number, based on the molecular diffusion and heat diffusion, n / a - ratio was computed to be 0.70. The outcomes obtained in the experimental campaign successfully described the local Nusselt number as ...

Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering, 2020

International Journal of Mechanical and Materials Engineering, 2020

This work aims for a novel thermoelastic analysis methodology based on experimental steady-state ... more This work aims for a novel thermoelastic analysis methodology based on experimental steady-state temperature data and numerical displacement evaluation. The temperature data was acquired using thermal imaging and used as the input for a boundary element method (BEM) routine to evaluate its consequent thermoelastic displacement. The thermoelastic contribution to the resultant displacement arises in the BEM formulation as a domain integral, which compromises the main benefits of the BEM. To avoid the necessity of domain discretization, the radial integration method (RIM) was applied to convert the thermoelastic domain integral into an equivalent boundary integral. Due to its mathematical development, the resultant formulation from RIM requires the temperature difference to be input as a function. The efficacy of the proposed methodology was verified based on experimental displacement fields obtained via digital image correlation (DIC) analysis. For this purpose, a CNC (computer numeri...

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

Gold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late... more Gold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late TTG event at the core of calderas, producing small porphyries and gold-rich VMS deposits; (2) a sanukitoïd event, producing alkaline and felsic subvolcanic plutons with large gold hydrothermal systems, and (3) a hydrothermal/structural event. A large part of the gold mineralization may be directly related to the unique geodynamic situation, including the first subduction with two generations of gold-enriched intrusions.

XXVI Congresso Nacional de Estudantes de Engenharia Mecânica, 2019

17th Brazilian Congress of Thermal Sciences and Engineering, 2018