Tese: Performance evaluation of linear and non-linear eddy viscosity turbulence models to predict channel flow
Aluno(a) : Felipe Warwar MuradOrientador(a): Angela Nieckele e Luiz Eduardo Sampaio
Área de Concentração: Termociências
Data: 24/07/2018
Link para tese/dissertação: http://doi.org/10.17771/PUCRio.acad.35490
Resumo: The most popular models to solve turbulent flows are based on the Reynolds Average Navier Stokes approach (RANS), which needs closure equations to relate the Reynolds stress tensor to the mean kinematic tensors. The classical approach is the Boussinesq approximation that assumes a linear relation between the deviatoric part of the Reynolds stress tensor, and the rate of strain tensor. Previous works have shown, that the non-linear dependence on the rate of strain tensor can improve the model predictions. At the present work, first an evaluation of linear models available in the literature is performed, followed by the analysis of three higher order methods, that expands the tensorial basis to include other objective orthogonal tensors. Two different normalizations, one with the turbulent kinetic energy and dissipation rate and the other one with turbulent kinetic energy and the intensity of the rate of strain, had also been proposed for the models. The performance of the new models is assessed by comparing their numerical predictions to available channel flow and for a broad range of Reynolds Numbers. All models are implemented in the open source platform OpenFoam. Reasonable predictions of the Reynolds shear component of all models were obtained when compared with the DNS data. However, the non-linear models proved superior in the prediction of the other components. It was also observed that the model which depends non-linearly with the rate of strain and linearly with the non-persistence of strain was the one that best represented the DNS data field.