Electro-osmotic flow in a sector microchannel

The study presents analytical solutions of electro-osmotic flow in a sector microchannel with particular emphasis on the corner effects. The analytical solutions are obtained by the method of eigenfunction expansions in sequel for steady state, starting transient flow and oscillatory flow. It is shown that the smaller the opening angle is, the faster the flow approaches to steady state. For large nondimensional electrokinetic lengths, especially near an obtuse corner, a core of maximum velocity is soon established after the flow is started. The oscillatory flow exhibits phase lags between different modes that depend on their eigenvalues as well as the frequency of the externally applied voltage, hence distinguishing itself significantly from the steady state solution. This fact has an important physical implication about fast mixing of electrolytes in microchannels.