Wave number selection in a nonequilibrium electro-osmotic instability

Nonequilibrium electro-osmotic slip causes instability of quiescent ionic conductance through a diffusion layer of a strong electrolyte at a charge selective solid such as ion-exchange membrane or electrode. This instability, as inferred from the outer asymptotic limit of the full singularly perturbed ionic transport problem, is of the short-wave type. This latter is a serious shortcoming of the limiting model. In this Brief Report we show that inclusion in the model of the first asymptotic corrections yields a reasonable finite wavelength selection.