Predicting turbulent flows in butterfly valves with the nonlinear eddy viscosity and explicit algebraic Reynolds stress models

Abstract

The development of turbulence modeling is crucial for the numerical prediction of the flow behavior, especially for separation, stagnation, reattachment, recirculation, and streamline curvature of the flow through complex structures. In this study, the capability of turbulence models was estimated for predicting the flow in a butterfly valve. The explicit algebraic Reynolds stress model (EARSM) and nonlinear eddy viscosity model (NLEVM) were evaluated in terms of the velocity profile, turbulence intensity, and Reynolds stress, and their results were compared with those of the standard k-epsilon and renormalization group (RNG) models. A numerical validation was conducted with the flow past a backward-facing step as the benchmark test. Comparison with the validation test showed that the NLEVM accurately predicted the reattachment length. For the flow in a butterfly valve, the NLEVM and EARSM indicated a smaller velocity increase than the standard k-epsilon and RNG models in the recirculation area near the valve region. The NLEVM and EARSM demonstrated an ability to predict anisotropic stresses with a dominant stress value near the valve region.