圆管流动的二次转捩

SECONDARY TRANSITION IN PIPE FLOW

利用直接数值模拟方法求解N-S方程来研究空间发展的圆管转捩,计算中雷诺数Re选定为3000。在局部壁面引入的周期性吹吸(PSB)扰动作用下,圆管中首先出现了塞流结构,并向下游迁移,同时有稳定的流向条带结构形成;在塞流结构离开计算域后,随着扰动的不断发展,流向条带结构逐渐破裂失稳,圆管流动出现了第二次转捩,这是一种新的转捩形式,我们称之为“二次转捩”。

The transition in spatially evolving pipe flow at Re=3000 is studied by direct numerical simulation of Navier-Stokes equation. By the disturbance imposed from the pipe wall in the form of periodic suction and blowing (PSB), slug structures that travel downstream are generated. Meanwhile, steady streamwise streaky structures are formed. After the slug structure moves out of the computational domain, with the development of the disturbance, the streamwise streaky structures lose their stability and break down, and the transition occurs again. This is a new kind of transition, and is referred to as secondary transition.