PRESENT STATUS OF 2ND-ORDER CLOSURE TURBULENCE MODELS - I - OVERVIEW

An overview of the second-order closure turbulence models is presented in this paper. Models studied include the k-epsilon-eddy viscosity mo del, k-epsilon-nonlinear Reynolds stress model, differential Reynolds stress model, k-epsilon algebraic stress model, near-wall second-order closure model, low-Reynolds number model, two-layer model, and multis cale model, which cover the efforts of scientists and engineers over t he past 50 years. However, at the present time, there exists no unifie d turbulence model. Each model applies successfully to some turbulent flows, while it predicts unsatisfactory results for other flows, espec ially for flows that are very different from those for which the model s were calibrated. To improve the prediction accuracy and the applicab ility of the existing turbulence models, modifying, or even remodeling , the epsilon equation, the dissipation rate of turbulent kinetic ener gy, and pressure-strain terms of the Reynolds stress, <(u(i)u(j))over bar>, equations is necessary.