Using an in-house finite element code, we analyzed the isothermal flow field of a polymer melt in a converging channel. More specifically, we calculated the mean strain function as a criterion for distributive mixing. The used power-law model is implemented to incorporate the shear thinning behavior of the polymeric melts. A parametric study is also presented to provide a good understanding of the complex dependency of the distributive mixing on rheological and geometrical parameters. Finally, an analytical solution for the mixing parameter is developed using some simplifying assumptions and curve-fitting techniques. (C) 2015 Society of Plastics Engineers