Study on three-dimensional complex turbulent flows

A family of interpolation schemes, including four-point third-order interpolation scheme (FPTOI) and four-point fourth-order interpolation scheme (FPFOI) has been proposed for approximating convective fluxes. The new schemes are evaluated through simulating the several flow problems. The predicted results show that two schemes have higher order accuracy and preserve a better stability behavior comparing with the QUICK scheme.; A higher-order bounded numerical scheme WACEB (Weighted Average Coefficients Ensuring Boundedness) is developed to approximate convective fluxes. The scheme has been applied to two turbulent flow problems. The simulations show that the WACEB scheme has at least the second-order accuracy while ensuring boundedness of solutions.; In the present study, a nonlinear k-ω model including the cubic terms is proposed to represent the anisotropy of Reynolds stresses and the effects of extra strain rates such as streamline curvature and body rotation. Four cases of turbulent flows are simulated numerically. The comparisons are made among the experimental data, numerical results with linear and nonlinear k-ω models. It is shown that the nonlinear k-ω model gives good agreement with data for curved, rotating and separated turbulent flows and heat transfer.; The turbulent flow inside a sharp U-bend is predicted by using the present nonlinear k − ω model and WACEB scheme. The calculated results by using both the non-linear k − ω model and the linear low-Reynolds number k − ϵ model (Launder and Sharma, 1974) have been compared with experimental data. It is shown that the present model produces satisfactory predictions of the flow development inside the sharp U-bend and well captures the characteristics of the turbulence anisotropy within the duct core region and wall sub-layer.; The fully developed turbulent secondary flows inside rotating square duct oriented at several angles with axis of rotation are numerically simulated using the present nonlinear k − ω models.