title: Is free surface free in micro-scale electrokinetic flows?
abstract: When a rigid boundary is replaced by a free surface, or by a liquid-liquid interface, the shear stress is reduced near the boundary because the no-slip on the rigid boundary is relaxed. A nonzero fluid velocity exists on the free surface, and the flow rate would increase by the replacement. For electrokinetic flows, however, the replacement from rigid to free boundary can lead to an increase (decrease) in shear stress (flow rate). This counterintuitive effect of free surface is presented in this note for a generic electroosmotic flow in a microchannel.
authors.affiliation: Department of Mechanical Engineering, POSTECH, Pohang, Republic of Korea.
authors.forename: WooSeok
authors.initials: W
authors.lastname: Choi
authors.forename: Ashtosh
authors.initials: A
authors.lastname: Sharma
authors.forename: Shizhi
authors.initials: S
authors.lastname: Qian
authors.forename: Geunbae
authors.initials: G
authors.lastname: Lim
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Joo
mesh_terms: D003198:Computer Simulation; D053841:Electroosmosis; D007700:Kinetics; D044085:Microfluidics; D033081:Shear Strength; D012996:Solutions / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D012996:Solutions; D012997:Solvents