物理学报2017，Vol.66Issue(20)：186-196,11.DOI:10.7498/aps.66.204702
三维边界层内诱导横流失稳模态的感受性机理
Receptivity mechanism of cross-flow instablity modes induced in three-dimensional boundary layer
摘要
Abstract
Boundary-layer receptivity is the initial stage of the laminar-turbulent transition process, which plays a key role in the transition, especially for the case of three-dimensional boundary-layer flow. The research of the three-dimensional boundary-layer receptivity is theoretically significant for further understanding of the mechanisms of laminar-turbulent transition and turbulence formation. A numerical method is used to study the three-dimensional boundary-layer re-ceptivity under the interaction of the free-stream turbulence and the three-dimensional localized wall roughness. Then whether a new cross-flow instability mode can be found in the three-dimensional boundary layer is studied. Subsequently, investigated are the conditions under which the steady or unsteady cross-flow instability mode can be induced in the three-dimensional boundary layer, the influences of the intensity, spanwise wave number and normal wave number of the free-stream turbulence, and the size and structure of the three-dimensional roughness on the three-dimensional boundary-layer receptivity under the free-stream turbulence interacting with the three-dimensional localized wall roughness, and the instability mode that can be induced and its role in the three-dimensional boundary-layer receptivity. The numerical results show that when the turbulence intensity is low, the steady cross-flow vortex excited by the three-dimensional localized wall roughness dominates the three-dimensional boundary-layer receptivity; on the contrary, when the turbu-lence intensity is high, the unsteady cross-flow vortex excited by the free-stream turbulence dominates the receptivity;additionally, when the interaction between the three-dimensional localized wall roughness and the free-stream turbulence is existent, three kinds of instability modes are all produced at the same time, namely, the steady cross-flow vortex, the unsteady cross-flow vortex and the new unsteady cross-flow vortex whose dispersion relation is equal to the linear combination of the positive and negative spanwise wave numbers of the first steady cross-flow vortex and the second unsteady cross-flow vortex. The in-depth research on the three-dimensional boundary-layer receptivity under the inter-action of the free-stream turbulence and the three-dimensional localized wall roughness is of benefit to accomplishing the hydrodynamic instability theory and the turbulence theory, and providing the theoretical foundation for the prediction and control of the laminar-turbulent transition.关键词
感受性/三维边界层/壁面局部粗糙/自由来流湍流Key words
receptivity/three-dimensional boundary layer/localized wall roughness/free-stream turbu-lence引用本文复制引用
陆昌根,朱晓清,沈露予..三维边界层内诱导横流失稳模态的感受性机理[J].物理学报,2017,66(20):186-196,11.基金项目
国家自然科学基金(批准号: 11472139)、江苏高校优势学科建设工程(批准号: PAPD)和南京信息工程大学人才启动基金(批准号:2016r046)资助的课题.Project supported by the National Natural Science Foundation of China (Grant No. 11472139), the Priority Academic Development Program of Jiangsu Higher Education Institutions, China (Grant No. PAPD), and the Startup Foundation for Talents of Nanjing University of Information Science and Technology, China (Grant No. 2016r046). （批准号: 11472139）
