湍流转捩模式研究进展

以湍流模式理论为基础发展起来的湍流转捩模式是一种十分重要的转捩预测方法. 本文对转捩模式的研究进行了回顾. 首先, 探讨了以低雷诺数湍流模式理论研究转捩问题的局限性,此类模式中, 用来模拟黏性层次的阻尼函数经过修正之后, 具有一定的转捩预测能力. 但也有观点认为这只是一种数值上的巧合而已. 其次, 指出了考虑间歇性的模式所存在的问题. 此类模式通过各种方式将间歇因子与湍流模式进行耦合, 在一定程度上考虑了转捩的物理机制, 可较好地模拟简单流动中的转捩过程. 但其中所包含的非局部变量使其与现代CFD方法并不协调一致. 接着, 分析了完全由局部变量构造的新型转捩模式, 其中涉及了关于非湍流脉动动能等转捩特征变量的新型输运方程. 最后, 对此领域的发展方向进行了预测. 

PROGRESS IN TURBULENCE/TRANSITION MODELLING

One of the effective approaches to simulating laminar-turbulent transition flows is the transition/ turbulence modeling based on Reynolds-averaged Navier-Stokes equations.In this paper,its development is reviewed.First,we analyze the limitations of the so called low-Reynolds number turbulence models for transitional flows.These models,with modified damping functions for the viscous sublayer,seem to have some ability for transition prediction,while it is argued that it is just a chance coincident in numerical simulation. Second,the correlation-based transition models are discussed.These models,always constructed by considering the intermittency factor,take into account the physical mechanism of transition in some extent,thus can model the transition procedure in several simple flows.Unfortunately,it is not easy to make these models compatible with modern CFD methods because of the non-local variables in model equations.Thirdly,based completely on local variables,some recently proposed transition models related to the new transport equations of laminar kinetic energy,transitional momentum thickness,Reynolds number and other characteristic parameters are analyzed.Finally,the future challenges are pointed out.