Enhancement of stirring in a straight channel at Low Reynolds-numbers with various block-arrangement
- 113 Downloads
In this study a newly designed microchannel as an efficient fluid-mixer is proposed. This design is comprised of a channel and a series of blocks periodically attached on the bottom surface of the channel. In this configuration, the stirring is greatly enhanced at a certain range of parametric values. To characterize the flow field and the stirring effect, both numerical and experimental methods were employed. To obtain the velocity field, three-dimensional numerical computation to the Navier Stokes equations was performed by using a commercial code, FLUENT 6.0. The fluid-flow solutions were then cast into studying the characteristics of stirring with the aid of Lyapunov exponent. In this study, the Lyapunov exponents were computed manually because the commercial code does not provide the corresponding tool. In the experiment, flow visualization was performed by using pure glycerin in a tank and glycerin mixed with small amount of a fluorescent dye in the other tank. The numerical results show that the pattern of the particles’ trajectories in the microchannel heavily depends on the block arrangement. It was shown that the stirring is significantly enhanced by a larger block-height and reaches maximum when the height is 0.8 times the channel width. We also studied the effect of the block stagger angle. It was found that stirring performance is the best at the block stagger angle of 45°.
Key WordsMEMS Micro Mixer Lyapunov Exponent
Unable to display preview. Download preview PDF.
- Kim, Y. J. and Kim, T. A., 2004, “A Study on the Plane Couette Flow Using Micropolar Fluid Theory,” KSME (Int.), Vol. 18, No. 3, pp. 491–498.Google Scholar
- Suh, Y. K. and Kim, Y. K., 1998, “Enhancement of Heat Transfer by Chaotic Advection in a Single Screw Extruder with a Staggered Flight Geometry,”Int. Proc. 11th IHTC, Kyongju, Korea, Vol. 5, pp. 399–404.Google Scholar
- Ottino, J. M., 1989,The Kinematics of Mixing: Stretching, Chaos, and Transport. Cambridge University Press.Google Scholar
- Ottino, J. M. and Shinbrot, T., 1999, “Comparing Extremes: Mixing of Fluids, Mixing of Solids,”in Mixing, Chaos and Turbulence, ed. by H. Chate et al., Kluwer Academic Pub.Google Scholar