Implementação, comparação e avaliação de modelos submalhas não lineares

Abstract

In the present work, the turbulence closure problem is analyzed by using a nonlinear subgrid-scale stress model, supposing a dependence on both the rate-of-strain and rate-of-rotation tensors. To understand how this dependence is established, in addition to analyzing different types of nonlinear models existing in the literature, is the scope of the current work. The inclusion of nonlinear terms, made in the present work, has the objective of learning about this complex way of modeling the turbulence closure problem. The work also has the objective of human resources training in the use of the MFSim code, developed on MFLab, and code development of computational models of turbulent flows on the same platform. To benchmark and evaluate the models, a computational implementation was conducted using the Large Eddy Simulation methodology for a simple problem of turbulent flow involving lid-driven cavity problem, which enabled a comparison between models implemented with experimental results found in the literature.The results obtained with the nonlinear models are in good agreement with the results of the physical experiments for flows that occurs near the walls. In contrast, the linear model better matches the results for flows in the central region of the cavity. As expected, the results obtained with the linear and nonlinear modeling did not differ significantly, since the physical nature of this problem does not incorporate effects such as high levels of anisotropy, pressure adverse gradients and even strong curvature effects on streamlines.