Smoothed Particle Hydrodynamic Study of Discontinuous Shear Thickening
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Despite the recent interest in the discontinuous shear-thickening (DST) behaviour, few computational works tackle the rich hydrodynamics of these fluids. In this work we present the first implementation of DST in Smoothed Particle Hydrodynamic (SPH) simulation. Scalar microstructural model was implemented in a SPH scheme and tested in two flow geometries. Stress-controlled simple shear tests have shown transient responses qualitatively congruent with experimental rheology of cornstarch including oscillations in measured shear rates within the range of transitional stress. Flow curves constructed from resulting data have shown good agreement with theory at the lower branch, and a minor disparity at the upper branch. The simulations were correctly able to capture the characteristic 'S-shape' curve, with the value of measured peak shear rate at the bend lower than expected. Within the range of transitional stress, apparent vorticity banding was observed. The lack of spatial correlation was attributed to the artificial planar constraints in the simulation. Velocity profiles obtained in body force driven channel flow were found to be in excellent agreement with the analytical solution, yielding an upward inflexion corresponding to the typical S-curve. Simulations carried out at increasing driving forces have exhibited a decrease in flow. We have shown that even the simply scalar model can capture some of the key properties of DST materials, laying foundation for further SPH study of instabilities and pattern formation.
