STRUCTURE OF AN ELECTRORHEOLOGICAL FLUID IN STEADY SHEAR

We report a real-time, two-dimensional light scattering study of the s tructure of an electrorheological fluid under steady shear. When an el ectric field is applied to the quiescent fluid, particles chain along the electric field lines and cause strong light scattering lobes to ap pear at a finite scattering wave vector q orthogonal to the field line s. We find that when the sample is subjected to steady shear a steady state scattering pattern emerges with lobes that are rotated in the di rection of fluid vorticity. The angle of rotation is found to increase as the cube root of the shear rate, in agreement with a theoretical p rediction of the steady state structure of fragmenting particle drople ts.