In electrochemical systems, ion-selective membranes and solid–liquid interfaces inevitably exhibit surface roughness, whose topological characteristics exert a pronounced influence on electroconvective flow in the near-interface region. In this study, we employ direct numerical simulations to systematically examine the impact of general rectangular roughness elements—parameterized by their height and spacing—on electroconvective flow and ion transport. The numerical results show good agreement with available experimental observations, thereby confirming the validity of the simulation framework. Further analysis demonstrates that, relative to smooth channels, surface roughness substantially reorganizes the near-wall vortex structures and markedly enhances their slip velocities. Both the ion transport efficiency and vortex intensity increase monotonically with increasing roughness height, whereas their dependence on the roughness spacing is non-monotonic, exhibiting an initial enhancement followed by attenuation. With appropriately designed membrane topographies, the ion transport efficiency can be enhanced by approximately 50%. This enhancement mechanism is governed by the modulation of local vortex dynamics arising from the overlap of extended space-charge layers between adjacent roughness elements. These results indicate that interfacial roughening offers an effective strategy for controlling vortical flow and ion transport in electrochemical systems.
Han et al. (Sun,) studied this question.