Analysis of the electric double layer effect on the microchannel flow stability

Sedat F. Tardu (1)

1 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

It is shown that the microchannel flow under the electric double layer (EDL) effect is inviscidly unstable. A classical Orr–Sommerfeld analysis revealed that the critical Reynolds number of the primary (linear) instability may decrease by a decade, provided that the liquid contains a very small amount of ions and is associated with large enough zeta potential and low conductivity/viscosity. When the EDL layer is thick, the inflexion point moves away from the viscous near wall region, and the inviscid instability mechanism becomes more dominant. The EDL modes are slower than the Poiseuille ones and the spectrum of the eigenvalues shows its strong destabilizing effect. There are some strong arguments suggesting that the nonlinear stability mechanism under the EDL effect is also more severe compared with the macroscale flow. The present investigation suggests that early transition in microchannel flows is plausible and can be checked through well-controlled experiments.

Mots clés: microfluidics; microchannels; EDL; linear stability; early transition

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Sedat F. Tardu. Analysis of the electric double layer effect on the microchannel flow stability. Microscale Thermophysical Engineering, 2004, 8 (4), pp.383-401. ⟨10.1080/10893950490516938⟩. ⟨hal-00262000⟩