Figure 11. Determination of the elastic instability criterion M2 at the onset of the first elastic instability at (Wic1,Rec1) for the 0.035 wt.% solution of PS16 in the OSCER device.
(a) dimensionless velocity field and hyperbolic streamlines determined using the ideal stream function for planar elongational flow. (b) dimensionless streamline curvature. (c) dimensionless streamwise stress determined from birefringence measurements made at Wi = 0.7, Re = 0.04. (d) Spatial distribution of M2 values obtained by combining data in parts (a) to (c) according to Eq. 1.