Control the Electroosmotic Flow through thermal effects
< Abstract >
A numerical investigation is conducted on the electroosmotic flow and associated heat transfer in a two-dimensional microchannel. The objective of this study is to explore a new conceptual idea that is control of an electroosmotic flow by using a thermal field effect through the temperature-dependent physical properties. The results of numerical computations showed that a proper control of thermal field may be a viable means to manipulate various non-plug-like flow patterns. A constant vertical temperature difference across the channel produces a shear flow. The horizontally-varying thermal condition results in spatial variation of physical properties to generate fluctuating flow patterns. The temperature variation at the wall with alternating vertical temperature gradient induces a wavy flow.
Eq. 1 Description of the temperature dependent Electroosmotic velocity
Fig. 1 Sketch of the model problem of a 2D microchannel between two plates with temperature variations
Fig. 2 Variations of the physical properties with temperature. Each property is normalized by the respective value at 15oC
Fig. 3 Comparison between numerical solution and analytical solution.
Fig. 4 Numerical results showing for the structure of EOF in a microchannel with horizontally-periodic wall temperature variations. The phase difference between the upper and lower wall temperature variations is (a); (b); and (c). Isothermal contours are normalized for ΔT=40K.
Related publication: Ho Sang Kwak, Hyoungsoo Kim, Jae Min Hyun, and Tae-Ho Song, "Thermal control of Electroosmotic Flow in a Microchannel through Temperature-Dependent Properties," JCIS, Vol. 335, 2009, 123-129, (DOI: http://dx.doi.org/10.1016/j.jcis.2009.03.008)