Investigação da estabilidade de escoamentos de jatos viscoelásticos
Carregando...
Arquivos
Data
2020-09-28
Autores
Sterza, Rafael de Lima [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O estudo do escoamento de jato é relevante devido à sua importância em aplicações industriais, tais como, sistemas de propulsão, troca de calor e massa e estabilização de tiras, placas e blocos durante o tratamento térmico por convecção. Diante disso, a instabilidade é investigada no presente trabalho para escoamentos bidimensionais de jatos incompressíveis, sendo o modelo Oldroyd-B adotado para o fluido viscoelástico. A Teoria de Estabilidade Linear é empregada para analisar o comportamento do escoamento de jato e, em particular, investigar os diferentes modos de instabilidade de Kelvin-Helmholtz. Para estudar a estabilidade do escoamento, é necessário conhecer o escoamento base, todavia há dificuldades em determiná-lo analiticamente para o problema de jato viscoelástico e, diante disso, utilizou o software OpenFOAM para simular o escoamento numericamente, com o objetivo de estudar o comportamento do jato laminar em termos de como evolui a jusante, a fim de confirmar a hipótese de escoamento paralelo e validar a utilização de uma aproximação canônica para o perfil de velocidade base. Com a finalidade de avaliar as taxas de amplificação máxima e as curvas neutras de estabilidade, diferentes simulações numéricas foram realizadas variando os parâmetros adimensionais para o escoamento de jato viscoelástico e comparando com os resultados de estabilidade de jato viscoso e de não viscoso.
The study of jet flow is relevant due to its importance in industrial applications such as propulsion systems, heat and mass exchange and stabilization of strips, plates and blocks during convection heat treatment. Therefore, instability is investigated in the present work for two-dimensional incompressible jet flows, and the Oldroyd-B model was adopted for viscoelastic fluid. The Linear Stability Theory is employed to analyze the jet flow behavior and, in particular, to investigate the different Kelvin-Helmholtz instability modes. In order to study the flow stability, it is necessary to know the base flow, however there are difficulties in determining it analytically for the viscoelastic jet problem and, therefore, OpenFOAM software was used to simulate the flow numerically in order to study the behavior of the laminar jet in terms of how it evolves downstream in order to confirm the hypothesis of parallel flow and validate the use of a canonical approach for the base velocity profile. In order to evaluate the maximum amplification rates and the neutral stability curves, different numerical simulations were performed varying the dimensionless parameters for viscoelastic jet flow and comparing with the results of viscous and non-viscous jet flow stability.
The study of jet flow is relevant due to its importance in industrial applications such as propulsion systems, heat and mass exchange and stabilization of strips, plates and blocks during convection heat treatment. Therefore, instability is investigated in the present work for two-dimensional incompressible jet flows, and the Oldroyd-B model was adopted for viscoelastic fluid. The Linear Stability Theory is employed to analyze the jet flow behavior and, in particular, to investigate the different Kelvin-Helmholtz instability modes. In order to study the flow stability, it is necessary to know the base flow, however there are difficulties in determining it analytically for the viscoelastic jet problem and, therefore, OpenFOAM software was used to simulate the flow numerically in order to study the behavior of the laminar jet in terms of how it evolves downstream in order to confirm the hypothesis of parallel flow and validate the use of a canonical approach for the base velocity profile. In order to evaluate the maximum amplification rates and the neutral stability curves, different numerical simulations were performed varying the dimensionless parameters for viscoelastic jet flow and comparing with the results of viscous and non-viscous jet flow stability.
Descrição
Palavras-chave
Escoamento de jato, Instabilidade de Kelvin-Helmholtz, Teoria de estabilidade linear, Fluido Oldroyd-B, Jet flow, Kelvin-Helmholtz instability, Linear stability theory, Oldroyd-B fluid