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Murad, Felipe Warwar; Sampaio, Luiz Eduardo Bittencout (Co-Advisor); Nieckele, Angela Ourivio (Advisor). Performance evaluation of nonlinear explicit algebraic Reynolds stress models to predict channel flows. Rio de Janeiro, 2018. 91p. Dissertação de Mestrado Departamento de Engenharia Mecânica, Pontifícia Universidade Católica do Rio de Janeiro. 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 nondimensionalization, 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 nonlinearly with the rate of strain and linearly with the non-persistence of strain was the one that best represented the DNS data field.

PERFORMANCE EVALUATION OF NONLINEAR EXPLICIT ALGEBRAIC REYNOLDS STRESS MODELS TO PREDICT CHANNEL FLOWS