Evolution of hairpin vortices in a shear flow

Recent experimental studies suggest that the hairpin vortex plays an important (and perhaps dominant) role in the dynamics of turbulent flows near walls. In this study a numerical procedure is developed to allow the accurate computation of the trajectory of a 3-D vortex having a small core radius. For hairpin vortices which are convected in a shear flow above a wall, the calculated results show that a 2-D vortex containing a small 3-D disturbance distorts into a complex shape with subsidiary hairpin vortices forming outboard of the original hairpin vortex. As the vortex moves above the wall, it induces unsteady motion in the viscous flow near the wall: numerical solutions suggest that the boundary-layer flow near the wall will ultimately erupt in response to the motion of the hairpin vortex and in the process a secondary hairpin vortex will be created. The computer results agree with recent experimental investigations

Preliminary Candidate Advanced Avionics System (PCAAS)

Specifications which define the system functional requirements, the subsystem and interface needs, and other requirements such as maintainability, modularity, and reliability are summarized. A design definition of all required avionics functions and a system risk analysis are presented

In Memoriam: The Honorable Leroy Rountree Hassell, Sr.

Leroy Rountree Hassell, Sr. passed away on February 9, 2011. News of his death devastated those of us associated with him onthe Supreme Court of Virginia. We had lost a dear friend, one always conscious of the needs of his associates and anxious about making sure they were comfortable. Even more, the court lost its peerless leader, and the people of the Commonwealth of Virginialost a dedicated public servant. He will be sorely missed in allcorners of our great state