Vortex-Surface Interactions: Vortex Dynamics and Instabilities
Abstract
Of central importance to this research program are the dynamics and instabilities of streamwise vortices interacting with surfaces. Of primary interest are not only the discovery of new natural instabilities coming from vortex-vortex or vortex-surface interactions, but also ultimately the possibility to control these flows. Applications of such flows include tip vortices and junction vortices interacting with hull surfaces, their interaction with boundary layers, as well as design of vortex generators to modify surface pressures. We find a short wave instability of the secondary vortices that are created by the interaction of the primary vortices with a wall (e.g. Harris & Williamson, 2012. J. Fluid Mechanics). Further research concerns the influence of a wall on the long wavelength instability in a vortex pair. Three regimes are found, depending on the initial height of the vortex pair above the wall. The key to the significant reorganization of vortex structure, is the rapid circulation decay at regions along the vortex span which first come into contact with the wall, causing strong axial pressure gradients and periodic axial flows. The process of vortex reconnection causes vortex rings to rise away from the surface, in a 3D version of the "vortex rebound" in 2D vortex dynamics. Many of the discoveries of phenomena in this work are seen for the first time, and lead to a number of publications (including 2 papers for J. Fluid Mechanics). Also, during the period of this research, we have been invited to write a review paper on vortex pair dynamics for Annual Review of Fluid Mechanics, which will appear in 2016 (Leweke, LeDizes & Williamson, 2016).
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 16, 2015
- Accession Number
- ADA627306
Entities
People
- Charles H. Williamson
Organizations
- Cornell University