Electroosmosis with Step Changes in Zeta Potential in Microchannels.

The article presents an analytical solution for two-dimensional fluid flow in a rectangular microchannel in the vicinity of a step change in the zeta potential. In the study, the stream function is determined from the creeping flow approximation to the Navier-Stokes equations assuming a fixed volumetric axial flow, a constant electric field, and thin symmetric double layers. The resulting biharmonic equation is derived using a double-sided Laplace transformation, which is then inverted by Heaviside expansion.