Supersonic air-scoop flows of a weakly ionized gas in external electromagnetic field

Redox-Magnetohydrodynamics for Microfluidic Control: Remote from Active Electrodes and Their Diffusion Layers

“…Outline of results.-Figure 1 illustrates the apparatus used to perform the magnetoconvection studies. When a 30 μA constant current was applied across the solution between the 3-mm long electrodes separated by 17.5 mm, an ionic current density, j, was established, where oxidation of Fe(CN) 6 4− to Fe(CN) 6 3− occurs at the anode and reduction of Fe(CN) 6 3− to Fe(CN) 6 4− occurs at the cathode. Microbead movement in the xy-plane varied in direction and speed by position.…”

“…In particular, in our experiments the magnet is distant from the active electrodes, so there are no net redox reactions or changes in solution composition that occur over the magnet. Thus, j there must be carried by all ions present (K + , Fe(CN) 6 3− , Fe(CN) 6 4− , and Cl − ) due to migration (charge compensation and the effect of the electric field). Additionally, the active electrode separation of 17.5 mm is 22 times the height of the electrochemical cell and almost twice its width, and the active electrode lengths of 3 mm are roughly one-third the width of the cell (cf.…”

“…This MHD force, F B (N m −3 ), occurs when charged particles move at right angles to a magnetic field and is calculated as the cross product F B = j × B, where j represents ionic current density (A m −2 ) and B is magnetic induction (T). [1][2][3][4] In MHD, the moving charges can be those in ionized gas (plasma), 5,6 electronic current in liquid metals, 7 and ionic current in molten 8 and solvent-dissolved [1][2][3]9,10 salts. Its effect is to alter the direction of the moving charge, imparting momentum to the surrounding fluid, and so leads to increased mass transfer.…”