Assessment of the reliability of two-equation URANS models in predicting a precessing flow

Abstract

A systematic assessment of unsteady Reynolds-averaged Navier–Stokes (URANS) models in predicting the complex flow through a suddenly expanding axisymmetric chamber is reported. Five types of URANS models assessed in the study comprise the standard k–ε model, the modified k–ε (1.6) model, the modified k–ε (1.3) model, the renormalization group (RNG) k–ε model, and the shear stress transport (SST) model. To assess the strengths and limitations of these models in predicting the velocity field of this precessing flow, the numerical results are assessed against available experimental results. Good agreement with the flow features and reasonable agreement with the measured phase-averaged velocity field, energy of total fluctuation and precession frequency can be achieved with both the standard k–ε and the SST models. The degree of accuracy in predicting the rate of both spreading and velocity decay of the jet was found to greatly influence the prediction of the precession motion.