Faraday instability in a miscible interface

Authors: William Batson, Farzam Zoueshtiagh, Sakir Amiroudine, Ranga Narayanan, "Immiscible interface vs. miscible interface in Faraday instability," ArXiv, 14 Oct 2010: http://arxiv.org/abs/1010.2835 The video depicts the dynamics of a Faraday instability for both a miscible and an immiscible interface. The instability occurs when the system is subject to vibrations of sufficient amplitude at a given frequency. If the amplitude exceeds a critical value, a deflection of the interface appears and grows in time. In the miscible case presented here, water is carefully placed on top of brine and is shaken at a frequency of 3 hz with an amplitude of 40 mm. With surface tension absent, the instability is driven by the density difference of the two phases. In the immiscible case, a 10 cSt silicone oil is placed on top of a uorinated compound called FC 70, and is shaken at a frequency of 7 hz and an amplitude of 3 mm. While the inclusion of surface tension can help stabilize the deflection to a steady, standing wave pattern, this video shows the shaking can still be violent enough to induce mixing.