Key structure in laminar-turbulent transition of boundary layer with streaky structures
Key structure in laminar-turbulent transition of boundary layer with streaky structures
复制标题
条纹结构边界层层流-湍流转变的关键结构
DOI：
10.1016/j.taml.2019.01.005
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发表时间：
2019
影响因子：
3.4
通讯作者：
Fukunishi Yu
中科院分区：
文献类型：
--
作者：
Yoshikawa Joe;Nishio Yu;Izawa Seiichiro;Fukunishi Yu
对层流-湍流转捩过程中的一个关键涡结构进行了数值模拟。一个低速条纹内产生的层流边界层使用一个孤立的长方体粗糙度，旨在提供一个不稳定的外部干扰的环境。然后，一个短的持续时间喷流发出到边界层。当喷流速度较低时，边界层中出现一些旋涡，但边界层不发生转捩。然而，当射流速度超过一定阈值时，在V形涡的细长腿上方新出现两个涡，并且只有其中一个被拉伸并存活。之后，在幸存者周围产生了一个又一个的漩涡。通过比较衰减涡和残存涡的变化，发现两者的高度差是导致转捩的关键特征。
A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed at providing an environment unstable to outer disturbances. Then, a short duration jet is issued into the boundary layer. When the jet velocity is low, some vortices appear in the boundary layer, but the transition of the boundary layer does not take place. However, when the jet velocity exceeds a certain threshold, two vortices newly appear above the elongated legs of a V-shaped vortex and only one of them is stretched and survives. After that, vortices are generated one after another around the survived one. By comparing the decayed and the survived vortices, it is found that the difference in their heights is the key characteristic which leads to the transition.