Two‐dimensional laminar‐flow analysis, utilizing a doubly refracting liquid

An experimental technique for the determination of velocity distributions in two‐dimensional laminar flow is described. The method utilizes the optical interference patterns observed in flowing doubly refracting liquids when viewed by transmitted polarized light. The fluid shear‐stress distribution may be determined from these interference patterns by methods similar to those employed in solid photoelasticity. Methods are presented for the calculation of velocity distributions from the observed stress distributions. Experiments are described in which the technique was applied to determine velocity profiles in parallel‐walled, converging and diverging channels and for flow about a cylindrical obstacle. The doubly‐refracting liquids employed were aqueous solutions of an organic dye. Independent experimental checks were obtained in most instances, and these are in satisfactory agreement with the calculated results.