Shear viscosity and order parameter dynamics of fluids near the critical point

We present a simple modification of the mode-coupling equations which relate the shear viscosity to the decay rate of order parameter fluctuations of simple fluids and binary mixtures near their critical points. By including the background Rayleigh linewidth in these equations, both the critical shear viscosity and the critical Rayleigh linewidth can be calculated with no adjustable parameters, using only background transport data and static critical properties. Our predictions are found to be in good agreement with presently available experimental data.