Stress distribution and drag force in creeping flow around a falling sphere. Measurement by a flow-birefringence technique

The distributions of the primary normal stress difference and the shear stress in creeping flow around a falling sphere were measured by a transmitted-light, flow-birefringence technique. Both distributions were qualitatively reasonable, but were considerably different from the exact solutions for a Newtonian fluid with the same viscosity in the vicinity of the sphere, because of the elastic effect. The drag force acting on the sphere was calculated and used to evaluate the measurements quantitatively.