Electro-osmotic flow in channel: effects of superhydrophobic surface structures sizing

Numerical study on electro-osmotic flow over superhydrophobic transverse grooves and ribs have been explored. With uncharged liquid-gas interface, smaller electro-osmotic axial flow is attained. The electro-osmotic axial flow is found to be significantly influenced by the gas area fraction and the normalized groove-rib spacing. In the presence of the liquid-gas interfaces, slip flows are observed over these interfaces, consistent with that reported in pressure-driven flow. As the flow is permitted in the vicinity of the liquid-gas interface, flow redistribution is observed along the channel. Higher bulk flow with reducing flow magnitude is observed close to the wall when solid wall is present, and vice versa. Despite the alteration of the axial flow, conservation of flow along axial direction is attained. To estimate the normalized electro-osmotic axial flow for this flow condition, a new correlation formulation is proposed to accurately predict the averaged axial flow magnitude for different values of gas area fraction and normalized groove-rib spacing in the range between 0.1 and 4.