📝 SummarXiv

Abstract

A microfluidic approach to probing the first normal stress difference from single-point pressure measurements in pulsatile shear flows is presented. Using an original experimental design, we examine the near-zero-mean pulsatile flow of polymeric solutions in a straight, deformable microchannel at low Reynolds and Womersley numbers. An important aspect of this work is that the enhanced fluid elastic stresses can be efficiently determined via the pressure shift from pressure-controlled large-amplitude pulsatile shear experiments. We find a scaling law that collapses pressure-shift data from viscoelastic fluids of different molecular weights onto a single master curve that can then be used to predict this phenomenology. Taken together, these results could help shed light on our understanding of the non-linear normal stress responses in time-dependent flows.