The disintegration of charged drop-pairs in an electric field

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This paper is concerned with the electrohydrodynamics of a process which may be responsible for the electrification of warm clouds. If two charged drops are separated in an electric field of strength E the mutual interaction of the polarisation and applied charged on the drops results in a field in their near surfaces which is different from and generally greater than that in the surface of an isolated drop. The value of E required to effect disintegration will therefore decrease rapidly as the separation of the drops is reduced. Taylor's spheroidal assumption and Davis's calculations of the enhancement of the field between a pair of spherical conductors have been employed in calculations of the field required to disintegrate one of a pair of drops of radii R 1 and R 2 carrying charges Q 1 and Q 2, whose line of centres was inclined at an angle ϑ with the vertical electric field. The polar and equatorial equilibrium conditions provided a quartic equation which could be solved numerically to find critical values of E(R 2 1 2 for various values of radii, charges and drop separation. The predicted values of E(R 2 1 2 required to effect disintegration agreed well with experimental values determined from photographs by Sartor and Abbott showing the separation at which a liquid bridge was formed between the near surfaces of a pair of charged drops falling in an electric field. Additional support for the accuracy of the computed disintegration criteria was provided by measurements made with pairs of drops suspended from mechanical supports. Theory and experiment agreed quite closely over a wide range of values of Rin1, Rin2, Qin1 Qin2, ϑ and drop separation.