"Simulations of 3D two-phase flows using adaptive methods and phase field models" / "Simulações de escoamentos tridimensionais bifásicos empregando métodos adaptativos e modelos de campo fase"

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This is the first work that introduces 3D fully adaptive simulations for a phase field model of an incompressible fluid with matched densities and variable viscosity, known as Model H. Solving numerically the equations of this model in meshes locally refined with AMR technique, we simulate computationally tridimensional two-phase flows. Phase field models offer a systematic physical approach to investigate complex multiphase systems phenomena such as fluid mixing layers, phase separation under shear and microstructure evolution during solidification processes. As interfaces are replaced by thin transition regions (diffuse interfaces), phase field simulations need great resolution in these regions to capture correctly the physics of the studied problem. However, this is not an easy task to do numerically. Phase field model equations have high order derivatives and intricate nonlinear terms, which require an efficient numerical strategy that can achieve accuracy both in time and in space, especially in three dimensions. To obtain the required resolution in time, we employ a semi-implicit second order discretization scheme to solve the coupled Cahn-Hilliard/Navier-Stokes equations (Model H). To resolve adequatly the relevant physical scales in space, we use locally refined meshes which adapt dynamically to cover special flow regions, e.g., the vicinity of the fluid interfaces. We demonstrate the efficiency and robustness of our methodology with simulations that include spinodal decomposition, the deformation of drops under shear and Kelvin-Helmholtz instabilities.

ASSUNTO(S)

adaptive mesh refinement conservative phase field models multinível-multigrid refinamento de malhas adaptativas biharmonic equation equação biharmônica método adaptativo adaptive method separação dos componentes de uma mistura bifásica multilevel multigrid semi-implicit methods métodos semi-implícitos modelos de campo de fase conservativos spinodal decomposition

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