Flow birefringence in complex fluids has long been viewed as a noninvasive probe for stress fields based on the stress-optic law. Experiments reveal that this law fails in unsteady flows, with birefringence only reflecting stress at large Deborah numbers, leading to a new framework that separates microscopic and macroscopic contributions.
- Daisuke Noto
- Kohei Ohie
- Yuji Tasaka
