International Research Fellow Awards Program: An Investigation of Secondary Vortex Structure in the Near Wake of a Circular Cylinder

[600313]博格国际研究员奖励计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持John P. Borg博士在英国剑桥大学与Mike Gaster博士进行为期12个月的博士后研究访问。这项研究将有助于在临界雷诺数（65Re1200）或附近的圆柱上扩展非突发性近尾迹控制技术。在此过程中，本研究将促进对过渡的基本理解，包括位置，因果关系和机制。本研究希望定位和确定被认为是Tollmien-Schlichting波的二次涡系统的起源，以及相应的临界点，这些临界点被认为是在近尾迹中形成并导致一次涡的卷起。提出了剪切层中的气动控制端口和跨向声激励，以阻止二次系统的生长并将临界雷诺数扩展到电流限制之外。此外，还提出了一种描述主涡系统和次涡系统相互作用的动力系统。这样一个系统将用于发展过渡和湍流的分析模型。＊＊＊

9600313 Borg The International Research Fellow Awards Program enables U.S. scientists and engineers to conduct three to twenty- four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit by Dr. John P. Borg to work with Dr. Mike Gaster at the University of Cambridge in the United Kingdom. This research will serve to extend non-obtrusive near wake control techniques over circular cylinders at or near critical Reynolds numbers (65Re1200). In so doing, this research will advance the fundamental understanding of transition, including location, causality and mechanisms. This research hopes to locate and identify the origin of a secondary vortex system, believed to be Tollmien-Schlichting waves, and the corresponding critical points, which are believed to form in the near wake and result in roll-up of the primary vortex. Pneumatic control ports in the shear layer and spanwise acoustic excitation are proposed to hinder the growth of the secondary system and extend critical Reynolds beyond current limits. In addition, a dynamical system is proposed to describe the interaction of both the primary and secodary vortex system. Such a system is to be used to develop an analytical model of transitional and turbulence. ***