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 Re is between 0.002 and 0.01, while it is enhanced when Re 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 Wi ≤ 20, while a larger mixing degree is realized at a higher pulsing frequency when Wi = 50.

A cost-effective serpentine micromixer utilizing ellipse curve

“…Furthermore, the intensity of Dean vortices can be quantitatively evaluated by Dean number (De), defined as Eq. (10).…”

“…pressure [9], thermal [10] and magnetic fields [11] to agitate the flow fields and promote mixing. Passive micromixers utilize specially designed structures to disturb the flow fields and generate chaotic advection.…”

Artificial diffusion in the simulation of micromixers: A review

“…Passive micromixers have a chaotic structure 29,30 or planar shapes 31,32 and do not need external actuation to enhance the mixing quality. Active mixers employ external sources of energy, including magnetophoretic force, 33,34 electroosmotic force, 35,36 acoustic force, 37,38 thermal power 39,40 and periodic pressure perturbation 41,42 to perturb the flow filed. The FD and FV approaches have been used to discretize the differential governing equations.…”

Flow Direction-Dependent Elastic Instability in a Symmetry-Breaking Microchannel

“…As a result, various complex flows such as turbulent flow, Couette flow, or swirling flow can be obtained in viscoelastic fluid even at the micrometer scale [6][7][8][9]. Analytically, complex flow can be understood from the Navier-Stokes equation, whereby the nonlinearity of Newtonian fluid depends on the advective term in the equation, while viscoelastic fluid nonlinearity is also contributed by the rheological effects from the normal stress in the fluid [10], which can be applied for mixing [11,12] or sorting [13] in microfluidics.…”