Chaotic Micromixer Based on 3D Horseshoe Transformation

To improve the efficiency of mixing under laminar flow with a low Reynolds number (Re), a novel three-dimensional Horseshoe Transformation (3D HT) was proposed as the basis for the design of a micromixer. Compared with the classical HT, the Lyapunov exponent of the 3D HT, which was calculated based on a symbolic dynamic system, proved the chaotic enhancement. Based on the 3D HT, a micromixer with a mixing length of 12 mm containing six mixing units was obtained by sequentially applying &#8220;squeeze&#8221;, &#8220;stretch&#8221;, &#8220;twice fold&#8221;, &#8220;inverse transformation&#8221;, and &#8220;intersection&#8221; operations. Numerical simulation and Peclet Number (Pe) calculations indicated that when the squeeze amplitude 0 &lt; <i>&#945;</i> &lt; 1/2, 0 &lt; <i>&#946;</i> &lt; 1/2, the stretch amplitude <i>&#947;</i> &gt; 4, and Re &#8805; 1, the mass transfer in the mixer was dominated by convective diffusion induced by chaotic flow. When Re = 10, at the outlet of the mixing chamber, the simulated mixing index was 96.4%, which was far less than the value at Re = 0.1 (<i>&#963;</i> = 0.041). Microscope images of the mixing chamber and the curve trend of pH buffer solutions obtained from a mixing experiment were both consistent with the results of the simulation. When Re = 10, the average mixing index of the pH buffer solutions was 91.75%, which proved the excellent mixing efficiency of the mixer based on the 3D HT.

Abstract licence: CC BY

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