In the present study, experiments are performed to determine the changes in the viscosity of water-Fe3O4 magnetic
nanofluid (MNF) with shear rate, nanoparticle concentration and magnetic field (MF) induction. Itwas observed
that as the shear rate elevates, the MNF viscosity first diminishes and then remains almost constant.
Besides, the viscosity elevated with the application of theMF and its induction and also with increasing the concentration
of nanoparticles. As another novelty of this research, a novel kernel based machine learning scheme
namely, grid optimization based-kernel ridge regression (Grid-KRR) modelwas developed to accurate prediction
of viscosity ofwater-Fe3O4MNF based on volume fraction of nanoparticles, shear rate, andmagnitude of external
MF as input features. Besides, the Randomforest (RF) and Gene expression programming (GEP) modelswere examined
for validating the Grid-KRR model. The performance criteria demonstrated that the Grid-KRR
outperformed the RF.