Optimal disturbances and bypass transition in boundary layers
Optimal disturbances and bypass transition in boundary layers
复制标题
DOI：
10.1063/1.869908
复制
发表时间：
1999
影响因子：
4.6
通讯作者：
P. Andersson;M. Berggren;D. Henningson
中科院分区：
文献类型：
--
作者：
P. Andersson;M. Berggren;D. Henningson
流向条纹在过渡边界层中是普遍存在的，特别是当受到高度的自由流湍流时。采用定常边界层近似，数值计算了上游扰动经历最大空间能量增长。计算使用的技术通常采用时，解决分布参数系统的最优控制问题。计算出的最佳扰动由发展成流向条纹的流向涡组成。发现最大空间能量增长与距前缘的距离成线性比例。在此基础上，提出了一个简单的转捩位置预测模型。可用的实验已被用来关联出现在模型中的单个常数。
Streamwise streaks are ubiquitous in transitional boundary layers, particularly when subjected to high levels of free-stream turbulence. Using the steady boundary-layer approximation, the upstream disturbances experiencing maximum spatial energy growth are numerically calculated. The calculations use techniques commonly employed when solving optimal-control problems for distributed parameter systems. The calculated optimal disturbances consist of streamwise vortices developing into streamwise streaks. The maximum spatial energy growth was found to scale linearly with the distance from the leading edge. Based on these results, a simple model for prediction of transition location is proposed. Available experiments have been used to correlate the single constant appearing in the model.