Isotropization and cosmological dimensional reduction in the cosmological models with a viscous fluid

After extending some existing solutions of the Bianchi type I cosmological models with a viscous fluid to higher-dimensional theory, we use a simple algorithm to determine all Hubble functions therein. Emphasis is placed on the fact that although the shear scale function shall always decrease with cosmic time t and approach zero faster than t^-2, both the non-positive Hubble function and non-negative Hubble function can be contained in a solution of some anisotropic cosmological models with viscosity. Thus the cosmological dimensional reduction may work in higher-dimensional cosmological models with a viscous fluid.