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The top picture was obtained using a holography technique [Meng & Hussain, Appl. Opt. 34, 1827 (1995)] and display a
nonlinear breakdown of a drop into water. The drop, aqueous polystyrene suspension with 90% water and 0.5cm in diameter, falls
freely from a distance of 1cm above the water surface. The drop undergoes vortex ring instability that cascade on smaller and
smaller scales (droplets, wakelets, ringlets) and yield flow crowns, 3D arcades and chaotic structures.
The bottom picture was taken
by J. J. Thompson and H. J. Newal in 1885, showing similar instabilities demonstrated by dye entering water.
References:
Estevadeordal, J., Meng, H., Gogineni, S., Goss, L., and Roquemore, M., "3D Visualization of Vortex-Ring and
Bag-Shaped Instabilities Using Holography", Phys. of Fluids (Gallery of Fluid Motion), 9, No.9, S5, 1997.
Meng, H., Estevadeordal, J., Gogineni, S., Goss, L., and Roquemore, M, "Holographic Flow Visualization, a Tool for Studying Three
Dimensional Coherent Structures and Instabilities", J. of Visualization, Vol. 1, 2, 133-144, 1998.
Contributor: Dr. Jordi Estevadeordal of ISSI.
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