Abstract
A catiomc surfactant,cetyltrimethylammonium bromide,CTAB,forms wormlike micells in aqueous solution with sodium salicylate,NaSal.Wormlike micelle solutions have viscoelastic characteristics originated from network of micells.Aqueous solutions of CTAB/NaSal systems are used as test fluid.To obtain full-field flow birefringence image of transient flows around a sphere moving linearly at a constant speed in aqueous surfactant solutions,a polarization-imaging camera is utilized.Left circularly polarized light is used as incident light and the degree of linear polarization(DOLP) and the angle of polarization(AOP) of transmitted light are measured.The measurements show the periodic process of growth and deterioration of high DOLP field behind a sphere at a Deborah number greater than a critical value.
