Miscible Fingering in Electrokinetic Flow

Analysis is carried out to examine the miscible fingering phenomenon when a fluid with a lower electrolyte concentration advances into one with a higher concentration. Unlike earlier miscible fingering theories, the linear stability analysis is carried out in the self-similar coordinates of the diffusing front. The dominant destabilizing mode is shown to be a localized concentration disturbance within the diffusive layer. However, transverse diffusion is shown to eventually stabilize the instability at time t=tc that scales as b8/3 where b is the breadth of the channel, and lengthen the dominant transverse wavelength as t3/8 in the interim. With these scaling laws, we arrive at the conclusion that transient fingering is insignificant in submillimeter micro-devices which use electrokinetic flow to transport biological and environmental electrolyte samples.

並列關鍵字

Micro-fluidics ； Electrokinetic flow ； Miscible fingering ； Diagnostic kits

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