not really - viscosity is so dependent on the exact nature of the intermolecular interactions that there really isn't a good theoretical model for determining viscosities of mixtures.
That being said, there are particular types of mixtures for which calculations have been developed. I have seen methods for calculating the viscosity of mixtures of polymers which have the same structure but different average molecular weights, and empirical methods for calculating viscosities of oils blended from proprietary formulations (essentially a graph of composition vs. viscosity from blending a high and low viscosity oil). These are mixtures of very similar compounds differing only in molecular weight, so the intermolecular interactions are as similar as possible.
I don't know what your particular application is, but if you contact the providers of your materials, they may know the viscosity dependence on mixing.