A method based upon Taylor dispersion theory is used to determine the shear-induced diffusion coefficient in concentrated suspensions. The experiments are performed in a cylindrical Couette device with a suspension consisting of polystyrene spheres in a density-matched solution of glycerin and water. A sequence of several hundred transit times for a single tagged sphere to complete successive orbits within the device is measured. The data are analyzed to compute the azimuthal Taylor dispersion coefficient from which the coefficient of shear-induced diffusivity is obtained. In our experiments the particle Reynolds numbers are script O sign (10-1). The experimental results are compared to the existing measurements of the shear-induced diffusion coefficient obtained at lower particle Reynolds numbers and based upon short-time data. We And a shear-enhanced diffusion coefficient D⊥/γ + ̇a2 = script O sign(0.1) for a volume fraction of Φ≈0.25; this is comparable to existing results from previous low particle Reynolds number studies (ℛ<10-3).
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Fluid Flow and Transfer Processes