Startup electroosmotic flow of a viscoelastic fluid characterized by Oldroyd-B model in a rectangular microchannel with symmetric and asymmetric wall zeta potentials

We study the startup flow of a viscoelastic fluid in a microfluidic channel, by considering the Oldroyd-B constitutive model. In particular, we aim to capture the confluence of the interfacial charge and the combined viscous and elastic properties of the fluid toward dictating the resulting startup flow characteristics. We further highlight the implications in the asymmetric nature of the wall zeta potentials on the flow behavior. We observe an increase in flow rate with increase in elastic nature of the fluid for studies with symmetric wall zeta potentials. For cases with asymmetric zeta potentials, we observe large movement of the velocity peaks, creating crests and troughs. Results from the present study may turn out to be useful in designing lab on a chip based microfluidic devices transporting bio-fluids such as blood, saliva and mucus by means of electroosmotic mechanisms.