Effect of viscoelasticity on the flow pattern and the volumetric flow rate in electroosmotic flows through a microchannel

Abstract

Many lab-on-a-chip based microsystems process biofluids such as blood and DNA solutions. These fluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids. Adopting appropriate constitutive equations these exotic flow behaviors can be modeled and predicted reasonably using various numerical methods. In the present paper, we investigate viscoelastic electroosmotic flows through a rectangular straight microchannel with and without pressure gradient. It is shown that the volumetric flow rates of viscoelastic fluids are significantly different from those of Newtonian fluids under the same external electric field and pressure gradient. Moreover, when pressure gradient is imposed on the microchannel there appear appreciable secondary flows in the viscoelastic fluids, which is never possible for Newtonian laminar flows through straight microchannels. The retarded or enhanced volumetric flow rates and secondary flows affect dispersion of solutes in the microchannel nontrivially.

Effects of non-Newtonian power law rheology on mass transport of a neutral solute for electro-osmotic flow in a porous microtube

“…This may be due to the interference of the pressure gradient on the electroosmotic flow profile of non-Newtonian fluid leading to origin of some sort of secondary flows. 62 Since, physiological fluids exhibit shear thinning behavior, the assisting flow should be preferred on account of enhanced mass transfer.…”

Transient electro-osmotic flow of generalized Maxwell fluids in a straight pipe of circular cross section

“…Furthermore, they presented a comprehensive review of electrokinetics pertaining to non-Newtonian fluids [11]. Park and Lee [12] derived a semi-analytical expression for the Helmholtz-Smoluchowski velocity under pure electroosmosis conditions for the full Phan-ThienTanner (PTT) constitutive equation, and they used a finite volume method to calculate numerically the flow of the full PTT model in a rectangular duct under the action of electroosmosis and a pressure gradient [13]. With the help of a Fourier transform, Bandopadhyay and Chakraborty [14] investigated the dynamical interplay between interfacial electrokinetics and a combined dissipative and elastic behavior of flow in narrow confinements.…”

Electro-osmotically actuated oscillatory flow of a physiological fluid on a porous microchannel subject to an external AC electric field having dissimilar frequencies

“…Figs. [15][16][17][18] indicate that with an increase in the value of S, which is the ratio of the suction velocity to the Helmholtz-Smoluchowski electro-osmotic velocity U HS , neither the steady state value nor the amplitude of oscillation of velocity, u, suffer any significant change. However, Figs.…”

“…Some further discussions on EOFs actuated by the application of electrokinetic forces are available in [10][11][12][13][14]. Park and Lee [15] presented an analysis of the problem of EOF of a viscoelastic fluid on a straight rectangular microchannel with-/-without pressure gradient. They observed that the volumetric flow rate of a viscoelastic fluid differs significantly from that of a Newtonian fluid under the action of the same pressure gradient-/-externally applied electric field.…”