Elastic secondary flows of semidilute DNA solutions in abrupt 90° micro-bends

Secondary flows that are absent in Newtonian flows are found for semidilute λ-DNA solutions in abrupt planar 90° microbends at modest levels of elasticity. Flow visualization and microparticle image velocimetry experiments show that a vortex, which is present in the inner, upstream corner of the bend, grows with increasing Reynolds and Weissenberg number (9.9×10−7−2,0.4