Nwosu et al.  presented a review and parametric investigation into nanofluid viscosity models. The purpose of the present discussion is to draw the attention of readers that Nwosu et al.  did not refer to some nanofluid viscosity equations, which are available in literature. Different examples for the missing nanofluid viscosity equations are given below.
Nwosu et al.  mentioned the empirical model of Maïga et al.  for ethylene glycol (EG)–γAl2O3 nanofluid. It should be noted that Nwosu et al.  did not mention the empirical model of Maïga et al.  for water–γAl2O3 nanofluid. This empirical model for water–γAl2O3 nanofluid was
Nwosu et al.  mentioned the...