  We propose a unifying mechanism based on the Stribeck curve for the
coefficient of friction between the particles to capture the shear thinning -
Newtonian plateau - shear thickening - shear thinning rheological behavior at
low - intermediate - beyond critical - high shear rates, respectively, for a
typical dense non-Brownian suspension. We establish the accuracy of the
proposed model by comparing the numerical results with experimental data. The
presence of non-DLVO (Derjaguin and Landau, Verwey and Overbeek) forces and a
coefficient of friction reducing with asperity deformation explain the
existence of the Newtonian plateau at the intermediate shear rates and the
second shear thinning regime at high shear rates, respectively.
