濃厚粒子分散系流体の流動反転時の粒子の過渡挙動

抄録

In this study, we have investigated transient responses generated with concentrated suspension of non-Brownian particles after a shear reversal between parallel plates. After a pre-shear flow with a constant shear rate, two types of subsequent flows were applied to the suspension. In the case of subsequent shear stress sweep flow, behaviors of respective particles in the shear flows were simultaneously visualized and correlations between the total responses and the particle behaviors are discussed. The concentrated suspension showed transient responses with temporal fluidity increase just after the shear reversal and the corresponding particle transient motions with apparent slipping phenomena near a moving and stationary plates were symmetrically observed. On the other hand, in the cases of subsequent constant shear rate flows, asymmetric behaviors of the particles were observed near the moving plate and the stationary one. Delayed growths in particle velocity were generated only near the stationary plate. We have obtained rapid increases in velocity near the moving plate as shown in the cases of restart flow with same direction.