Cavitation visualization of vorticity bridging during the merger of co-rotating line vortices

The flow of two co-rotating, merging line vortices was visualized with cavitation, and the images reveal the complex flow interactions associated with the vortex merger. While the developed cavitation has an influence on the vortical flow, the basic features of the noncavitating flow can be discerned through the judicious application of different free-stream cavitation numbers. By inducing vapor in the vortex cores, the existence of radial "bridging" vortices in the merger zone was confirmed. These visualizations are consistent with the numerically predicted vortex interactions presented by R. L. Bristol, J. M. Ortega, P. S. Marcus, and O. Savas [J. Fluid Mech. 517, 331 (2004)] and the experimentally inferred flow features are reported by A. L. Chen, J. D. Jacob, and O. Savas [J. Fluid Mech. 382, 155 (1999)] and W. J. Devenport, C. M. Vogel, and J. S. Zsoldos [J. Fluid Mech. 394, 357 (1999)]. (C) 2007 American Institute of Physics.