Electro-osmotic flow (EOF) is the motion of liquid induced by an applied electri

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Electro-osmotic flow (EOF) is the motion of liquid induced by an applied electric field across a charged capillary tube or microchannel. Assume the channel wall is negatively charged, a thin layer called the electric double layer (EDL) forms in the vicinity of the channel wall in which the number of positive ions is much larger than that of the negative ions. The net positively charged ions in the EDL then drag the electrolyte solution along with them and cause the fluid to flow toward the cathode. The thickness of the EDL is typically on the order of 10 nm. When the channel dimensions are much larger than the thickness of EDL, there is a slip velocity, y - epsilonzeta / mu E rightarrow, on the channel wall, where epsilon is the fluid permittivity, zeta is the negative surface electric potential, E rightarrow is the electric field intensity, and mu is the fluid dynamic viscosity. Consider a microchannel formed by two parallel plates. The walls of the channel have a negative surface electric potential of zeta. The microchannel is filled with an electrolyte solution, and the microchannel ends are subjected to an electric potential difference that gives rise to a uniform electric field strength of E along the x direction. The pressure gradient in the channel is zero. Derive the velocity of the steady, fully developed electro-osmotic flow. Compare the velocity profile of the EOF to that of pressure-driven flow. Calculate the EOF velocity using epsilon = 7.08 times 10-10 C middot V-1m-1, zeta = -0.1 V, mu=10-3 Pa middot s, and E = 1000 V/m. P5.97

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Electro-osmotic flow (EOF) is the motion of liquid induced by an applied electri

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