Contribution of frictional contact during steady and oscillatory shear in the discontinuous shear thickening fluid

In the present work, an elastic-core-modified mesoscale dissipative particle dynamics model is proposed, so as to investigate the microstructural evolution dependency on the viscosity in shear thickening fluids. The characteristic of the microstructural evolution in the colloidal suspensions under steady shear deformation is studied. The dominant interaction in the system changes from the hydrodynamics to the strong frictional contacts during the discontinuous shear thickening (DST) stage. An oscillatory shear action is creatively taken to study the rheological properties of the suspension, as well as to investigate the microstructural evolution with dynamic response of the system. The exact formulation of the relative viscosity as a function of the effective volume fraction (EVF), which is obtained from the packaging of the frictional contact network, is proposed. It is confirmed that the formation of frictional contact network of dispersed colloidal particles is determined by the competition between construction and decomposition of the particle contacts. The influences of different factors, like particle size, volume fraction, and surface roughness, on the DST behavior are also explored to prove our mechanism. The relationship of shear rate, frictional contact network, EVF, and apparent viscosity is revealed clearly.