Seeding of Görtler vortices through a suction and blowing strip
Seeding of Görtler vortices through a suction and blowing strip
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DOI：
10.1590/s1678-58782004000300003
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发表时间：
2004-09
影响因子：
2.2
通讯作者：
Leandro Franco de Souza;M. Mendonca;Marcello A. F. Medeiros;M. Kloker
中科院分区：
文献类型：
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作者：
Leandro Franco de Souza;M. Mendonca;Marcello A. F. Medeiros;M. Kloker
凹面边界层中戈特勒涡的波长由上游流动历史和壁面扰动决定，如粗糙度、加热/冷却条带或吸气和吹气。在各向同性扰动条件下，优势波长对应于线性稳定性理论预测的最强涡旋增长模。如果扰动环境不是各向同性的，则可能会出现波长不同于增长率最高的涡旋。本文研究了壁面吸吹条激励Gortler涡时的波长选择问题。该研究基于对由N-S方程导出的涡度输送方程的数值模拟。采用紧凑的高阶有限差分技术进行求解。结果表明，当涡旋在壁面上被吸气和吹气激发时，它们的波长并不一定与施加的波长相对应。给出了不同谐波扰动能量的流向发展曲线，揭示了主模的演化过程。文中还给出了WISE平面上流向速度的等值线，说明了高次谐波如何扭曲了特征蘑菇结构。
The resulting wavelength of Gortler vortices in boundary layers over concave surfaces is determined by the upstream history of the flow and by wall disturbances such as roughness, heating/cooling strips or suction and blowing. In isotropic disturbance conditions, the predominant wise wavelength corresponds to the strongest growing vortex mode predicted by the linear stability theory. If the disturbance environment is not isotropic, vortices with wavelength different from the one with the highest growth rate may emerge. The present investigation considers the wavelength selection when Gortler vortices are excited by a suction and blowing strip at the wall. The study is based on numerical simulations of the vorticity transport equations derived from the Navier-Stokes equations. They are solved using a compact high-order finite difference technique. The results show that, when the vortices are excited by suction and blowing at the wall, their wise wavelength does not necessarily correspond to the imposed wavelength. Curves of streamwise development of the disturbance energy for different harmonics are presented, showing the evolution of the dominant modes. Isolines of streamwise velocity in the wise plane are also presented, showing how the higher harmonics distort the characteristic mushroom structures.