Behaviour of miscible liquids under vibrations

The effects of vibrations on fluids are important in a wide range of scientific and engineering applications such as liquid storage, mixing, convection, pattern formation, and the study of basic fluid instabilities.

Vertical vibrations are the most studied case because the basic (unexcited) state is quiescent in a co-moving reference frame. Horizontally or obliquely vibrated systems, although more resistant to theoretical analysis, may be more relevant to the question of general fluid behavior than the more popular vertically forced Faraday system.

We present the new results on interface instability between miscible liquids when vibrations act either parallel to the interface or under 5-7° angle. The interface is represented as a transitional layer of small but nonzero thickness.  The considered mixtures represent the wide class of fluids: water-alcohol. We demonstrate both experimentally and theoretically not only that interface instability exists in miscible liquids but also strongly affect by the gravity.  The dependence of pattern formation and mixing on vibration forcing is discussed.