Electrically Induced Liquid–Liquid Phase Transition in a Floating Water Bridge Identified by Refractive Index Variations

Abstract

A horizontal electrohydrodynamic (EHD) liquid bridge (also known as a “floating water bridge”) is a phenomenon that forms when high voltage DC (kV·cm−1) is applied to pure water in two separate beakers. The bridge, a free-floating connection between the beakers, acts as a cylindrical lens and refracts light. Using an interferometric set-up with a line pattern placed in the background of the bridge, the light passing through is split into a horizontally and a vertically polarized component which are both projected into the image space in front of the bridge with a small vertical offset (shear). Apart from a 100 Hz waviness due to a resonance effect between the power supply and vortical structures at the onset of the bridge, spikes with an increased refractive index moving through the bridge were observed. These spikes can be explained by an electrically induced liquid–liquid phase transition in which the vibrational modes of the water molecules couple coherently.

Levitation by a dipole electric field

“…Utilizing advanced graph neural networks (GNN) [30,31] to structure GC as a graph will be helpful to learn about its external and internal interactions. Another future work may be to check whether the liquid-liquid transition asserted by Fuchs et al [32] also exists in GC. This research direction may provide a deeper understanding of the similarities and differences between levitating glycerol clusters and WBs, and their unique properties.…”

Low frequency weak electric fields can induce structural changes in water

“…When liquid water is subject to an inhomogeneous electric field (∇ 2 E a ≈ 10 10 V/m 2 ), enhancement of the vibrational collective modes, hindered rotational freedom of long range dipole–dipole interactions, and retardation of heat flow occurs, which eventually generates a chemical potential gradient in electrified water [ 22 ]. In other words, liquid water stressed by an electric field, exhibits primary signs of phase transition throughout the entire volume of liquid [ 23 ]. Previously, it was reported that water molecules tend to get ordered because of diminution in their translational entropy [ 1 , 24 , 25 ].…”

Dynamics of liquid mass transfer in a water bridge

“…One can see that, from the moment of the WB formation, the liquid flow through the bridge is first (during up to about 6 min) directed from the smaller−diameter electrode to that with larger diameter independently of their polarity; when the diameters are equal (a symmetric system), the mass is transferred in the forward direction (curve 1). Emphasize that all the works we have found about studying the dynamics of liquid flows through WB, including [1][2][3][4][5], demonstrate the predominance of the anode−to−cathode mass transfer. To our opinion, this is caused by predominantly using in those experiments plate electrodes whose sizes are comparable with the inter−electrode distance.…”

“…The water bridge (WB) arises between two dielectric cups with distilled water under the action of a constant high voltage applied between the electrodes submerged into the liquid [1][2][3][4][5][6][7]. The studies performed revealed a number of WB peculiar features [1][2][3]; one of the main features is the liquid transport through the bridge.…”

“…This repetitive flow reverse is a steady feature of the bridge; as assumed in [3,4], it is caused by the hydrostatic pressure induced by the difference in water levels in the cups. For the WB formation and stable existence, several models were suggested in [5]; however, besides [5], only one theoretical study concerning the flow inversion mechanism is known [6].…”