A Semianalytical Solution of Electroosmotic Microvortices in a Rectangular Conduit and Its Applications in Micromixer Design

• Main Authors: Chien-MingHuang, 黃健銘
• Other Authors: Shyh-Hong Hwang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/56220183519995105263

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 100 === This thesis investigates the construction of a micromixer using chaotic advection created by time-dependent electroosmotic microvortex flows for suspended particles in a rectangular conduit. The design principle is to modulate spatially and temporally the voltages of the electrodes embedded beneath the liquid-solid interface. Such modulation would form a specific time-dependent and nonuniform distribution of zeta potentials at the conduit’s walls and subsequently creates the required microvortex flows when subjected to external parallel electric fields. A two-dimensional semianalytical solution is proposed to compute accurately and rapidly the fluid velocities of electroosmotic flows in a confined rectangular cell. This solution combines an analytical solution for semicircular electroosmotic flows in the literature and the numerical solution along the semicircular arc on the bottom of the rectangular cell to derive four microvortex patterns. The four patterns consist of, respectively, a single vortex circulating across the entire cell, four counter-rotating vortices of equal size, two counter-rotating vortices on the upper and lower sides, and two counter-rotating vortices on the left and right sides. Simulation studies show that chaotic advection for particle mixing can be induced by periodically alternating between the first two flow patterns, while the best mixing efficiency can be achieved by properly selecting the period and the slip velocities at the conduit’s walls.