TY - GEN

T1 - Rate of decay of a passive scalar in a micro-mixer and the frequency of the advecting velocity fields

AU - Pacheco, J. Rafael

AU - Chen, Kangping

AU - Pacheco-Vega, Arturo

PY - 2009/12/1

Y1 - 2009/12/1

N2 - In the current work, the mixing of a diffusive passive-scalar, e.g., thermal energy or species concentration, driven by electro-osmotic fluid motion being induced by an applied potential across a micro-channel is studied numerically. Secondary time-dependent periodic or random electric fields, orthogonal to the main stream, are applied to generate cross-sectional mixing. This investigation focuses on the mixing dynamics and its dependence on the frequency (period) of the driving mechanism. For periodic flows, the probability density function (PDF) of the scaled passive scalar (i.e., concentration), settles into a self-similar curve showing spatially repeating patterns. In contrast, for random flows there is a lack of self-similarity in the PDF for the interval of time considered in this investigation. The present study confirms an exponential decay of the variance of the concentration for the periodic and random flows.

AB - In the current work, the mixing of a diffusive passive-scalar, e.g., thermal energy or species concentration, driven by electro-osmotic fluid motion being induced by an applied potential across a micro-channel is studied numerically. Secondary time-dependent periodic or random electric fields, orthogonal to the main stream, are applied to generate cross-sectional mixing. This investigation focuses on the mixing dynamics and its dependence on the frequency (period) of the driving mechanism. For periodic flows, the probability density function (PDF) of the scaled passive scalar (i.e., concentration), settles into a self-similar curve showing spatially repeating patterns. In contrast, for random flows there is a lack of self-similarity in the PDF for the interval of time considered in this investigation. The present study confirms an exponential decay of the variance of the concentration for the periodic and random flows.

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U2 - 10.1115/HT2009-88626

DO - 10.1115/HT2009-88626

M3 - Conference contribution

AN - SCOPUS:77952843637

SN - 9780791843581

T3 - Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009

SP - 527

EP - 535

BT - Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009

T2 - 2009 ASME Summer Heat Transfer Conference, HT2009

Y2 - 19 July 2009 through 23 July 2009

ER -