Electrohydrodynamic flow

Two-dimensional distributions of ground-state NO were detected by planar laser-induced fluorescence during the process of NO removal in a corona radical shower system in NO/dry air mixtures [57,58], The authors observed that the density of NO molecules decreased not only in the plasma region formed by the corona streamers and the downstream region of the reactor, but also in the upstream region of the reactor. They explained this behaviour by oxidation with ozone, which is transported upstream by electrohydrodynamic flow. 

Micron-sized polystyrene beads or nanometer-sized Au colloids suspended in water assembled into monolayers or multilayers on indium tin oxide by applying a voltage across two plates Electrohydrodynamic flow nm to (Jim 41,42... 

Electrokinetic effects are not usually of importance in the type of electrochemical experiments considered in this monograph, because the electric fields at the walls of the glass cells are small and significant convection is not induced. Although electrohydrodynamic flow can be induced by the interaction of an electric field with the diffuse layer near an electrode surface, the fields in the diffuse layer near the electrode surface are not sufficiently large in most electrochemical experiments to produce measurable fluid flow. However experiments in which very large fields are intentionally applied can produce... 

Electrokinetic/Electrohydrodynamic Flow Instability, Fig. 1 Left) Imaged particle paths for 0.49 pm-diameter fluorescent particles. The image intensity scale is inverted to better visualize the particle paths, (a) Stable oscillations at 1 kV. (b) Particles oscillate in plane with a transverse component at a larger applied voltage of 4 kV. 

Electrokinetic/Electrohydrodynamic Flow Instability, Fig. 3 Eiectrohydrodynamic mixing in a DC electric field. The images show the outlet branch of the microchannel after the device has been loaded with two fluids, (a) The initial condition showing a dark green fluid... 

Electrokinetic/Electrohydrodynamic Flow Instability, Fig. 5 (a) Schematic of the three-inlet geometry with electrodes and instability mixing. The channel height is 30 (tm, and the electrode to electrode spacing is 75 pm. (b) A stable flow in the absence of an electric field, (c) The disruption of flow after a 41 Vrms potential (initial applied field Eo = 8.2-10 V/m) is applied at 250 kHz to the electrodes, (d) EHD instability at 44 Vr s (initial applied field Eo = 8.8-10 V/m), 700 KHz. (e) Dispersion of the... 

With an increase in frequency, electrohydrodynamic instability can be found in a relatively wide voltage range, while the external field effect on orientation becomes less visible. When voltage is 25 V, the electrohydrodynamic flow begins to form once the frequency reaches 100 Hz. This kind of flow occurs in a wide frequency range, from 100 Hz to 60 kHz, as shown in Figure 2.30. The flow... 

Electrokinetic/ElectroHydrodynamic Flow Instability, Rgure 4 Plot of the negative imaginary (unstabie) roots of a> versus wavenumber using the viscous anaiysis for a variety of appiied fieids. The fiow is unstable as long as the root is negative imaginary [9]... 

Arifln DR, Yeo LY, Eriend JR (2007) Microfluidic blood plasma separation via bulk electrohydrodynamic flows. Biomicrofluidics 1(1). doi 10.1063/1.2409629... 

In calculating the threshold voltage, Hel-frich assumed that the spatial periodicity of the fluid deformation was proportional to the thickness of the cell. Penz and Ford [19-21] solved the boundary value problem associated with the electrohydrodynamic flow process. They reproduced Helfrich s results and showed several other possible solutions that may account for the higher order instabilities causing turbulent fluid flow. 

Neglecting the frequency response of the electrohydrodynamic flow, Helfrich calculated the threshold voltage for the domain instability. A slightly rewritten form of his expression is... 

H. Koelmans and A. M. VanBoxtel, Electrohydrodynamic Flow In Nematic Liquid Crystals, Moi Cryst. andUq. Cryst., 12, p. 185 (1971). 

---