Pressure Tap Influence on the Flow of Viscoelastic Fluids in a Microfluidic Channel

Abstract

How does flow inside a microfluidic device behave when passing by a pressure tap? Will its natural state be disrupted by any means? We seek to answer these questions and assess the consequences (if any) of attaching pressure taps to microchannels. To do so, streakline photography was performed for flow patterns visualisation in the close proximity of different types of pressure taps, using ‘long’ exposure times. Both a Newtonian and a viscoelastic fluid were tested, in order to observe the interplay of inertio-elastic effects near the intake of the pressure taps. The microdevices were made out of PDMS and the main flow channel, to which the pressure taps were attached, had a cross-section of $270\times 100$ $\upmu$m. Elastic effects were observed in the form of reduced streakline curvature near the taps intake and increased vortex formation.