Electrokinetic flow can be generated as a highly coupled phenomenon among
velocity field, electric conductivity field and electric field. It can exhibit
different responses to AC electric fields in different frequency regimes,
according to different instability/receptivity mechanisms. In this
investigation, by both flow visualization and single-point laser-induced
fluorescence (LIF) method, the response of AC electrokinetic flow and the
transition routes towards chaos and turbulence have been experimentally
investigated. It is found, when the AC frequency ff​<30 Hz, the interface
responds at both the neutral frequency of the basic flow and the AC frequency.
However, when ff​>=30 Hz, the interface responds only at the neutral
frequency of the basic flow. Both periodic doubling and subcritical
bifurcations have been observed in the transition of AC electrokinetic flow. We
hope the current investigation can promote our current understanding on the
ultrafast transition process of electrokinetic flow from laminar state to
turbulence