Comparison of Micro-Mixing in Time Pulsed Newtonian Fluid and Viscoelastic Fluid

Abstract

Fluid mixing plays an essential role in many microfluidic applications. Here, we compare the mixing in time pulsing flows for both a Newtonian fluid and a viscoelastic fluid at different pulsing frequencies. In general, the mixing degree in the viscoelastic fluid is higher than that in the Newtonian fluid. Particularly, the mixing in Newtonian fluid with time pulsing is decreased when the Reynolds number <i>Re</i> is between 0.002 and 0.01, while it is enhanced when <i>Re</i> is between 0.1 and 0.2 compared with that at a constant flow rate. In the viscoelastic fluid, on the other hand, the time pulsing does not change the mixing degree when the Weissenberg number <i>Wi</i> ≤ 20, while a larger mixing degree is realized at a higher pulsing frequency when <i>Wi</i> = 50.