In this paper, a study is undertaken to investigate the degree of variability between empirical nanofluid
viscosity data and the viscosity model predictions. It is seen that there is a high degree of variability in the
compared data, which suggests that a wide range of constitutive factors need to be incorporated into the
models in order to adequately account for the rheological behavior of nanofluids. A selection algorithm is
also proposed as a simple but effective tool for the model selection process in different nanofluidic conditions/
compositions; consequently the odds of redundancy are substantially reduced.