Confinement effects on the rotational microflows of a viscoelastic fluid under electrical double layer phenomenon

•Rotational microflow of a viscoelastic fluid under confinement effect.•Lateral confinement leads to vortex structures in the field under EDL effect.•Oldroyd-B model represenokts the rheology of the viscoelastic fluid.•Vortex formation dynamics enhances mixing in the microfluidic channel.

The last decade has seen a rise in the use of microfluidics based portable diagnostic devices, especially on the rotational platform (lab on a compact disc). One of the intrinsic problems with such devices is that experimental measurement of the flow fields and flow rates is difficult, owing to high rotational speeds. Hence, there is a need to computationally explore the flow and mixing involved in such devices and identify the optimal parameters of operation with respect to bio-fluids, many of which exhibit viscoelastic behavior. We, therefore, study the startup electro-osmotic flow of a viscoelastic fluid in a rotating rectangular microfluidic channel described by the Oldroyd-B model. The combination of the elastic and viscous nature of viscoelastic fluids brings out novel flow physics in a rotating rectangular microchannel, which we explore in detail. In particular, we show that the development of secondary flow in the channel due to the Coriolis forcing starts forming the vortex structures in the field aided by the lateral confinement of the channel, which may be of useful towards an enhancement in mixing in microfluidic devices.

Graphical AbstractDownload high-res image (85KB)Download full-size image