摘要
利用直接数值模拟研究圆管流动中由局部壁面引入的周期性吹吸(PSB)扰动沿流向的空间发展,流动的雷诺数Re选定为3000.在临界幅值的PSB扰动下,在较短的圆管内,圆管中的扰动沿流向快速增长,在足够长的圆管内,扰动沿流向持续增长发生转捩,流动发展到湍流阶段.
This paper studies the spatial evolution of the disturbance imposed from the pipe wall in the form of periodic suction and blowing (PSB) by direct numerical simulation at Reynolds number 3000. At critical amplitude of PSB, the disturbances are growing rapidly in a short pipe. And in long pipe, disturbances develop gradually, and then transition appears, flow develops to turbulence in sufficient long downstream distance.The results presented above describe the transition process in a smooth pipe flow with small external disturbances. At initial stage disturbances are developing by a mechanism of linear transient growth and then the nonlinear interaction produces longitudinal vortices. After overshooting the regular saturated disturbances are superimposed to the Hagen-Poiseuilli flow. This flow structure is unstable and will be easily perturbed with rapid growth. A new type of irregular disturbances is triggered strongly in a compact region and they become saturated again after the strong compact disturbances are dispersed downstream where the statistical properties of the flow agree with those in turbulent regimes. Whole process, which is emerging in sufficient long pipe, is consistent with the famous Reynolds experiment and it explain the reason why the previous numerical simulation failed to observe the transition to turbulence.
出处
《力学学报》
EI
CSCD
北大核心
2003年第1期6-13,共8页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金资助项目(19732005).
