Study of mixing efficiency in roll‐mills

A fluid dynamics analysis package (FIDAP) based on the finite element method was used to simulate the 2‐D, isothermal flow of a power law model fluid in the bank and nip area of a two roll‐mill geometry, including the determination of the free surface. Dispersive mixing efficiency was analyzed in terms of the shear stresses generated and the elongational flow characteristics. The latter were quantified using a frame invariant flow strength parameter. We found that the converging region rather than the nip region provides better mixing flow characteristics. We also found that the presence of vortices in the bank region is not beneficial for dispersive mixing.