论文标题
浓缩悬浮液撞击时变形
Deformation upon impact of a concentrated suspension drop
论文作者
论文摘要
我们研究了悬浮在牛顿液体中的板和一滴非胶体固体颗粒之间的影响，并特别注意粒子体积分数（$ ϕ $）接近 - 甚至超过 - 临界体积分数，$ ϕ_C $，在该质量稳定悬浮液的稳定粘度下。我们使用特定的浓度方案，并准确地确定每个液滴的$ ϕ $，并为不同的液体粘度，冲击速度和粒径测量变形$β$。在低体积分数下，$β$被发现遵循牛顿的有效行为，我们通过记录了高粘性牛顿下降的低变形极限，并表征了我们悬架的有效剪切粘度。相比之下，虽然有效的牛顿方法预测$β$在$ ϕ_c $下消失，但观察到有限的变形，以$ ϕ> ϕ_c $。这种有限的变形仍然由悬浮液粘度并随着粒径的增加而增加，这表明粒子相的扩张是耗散过程接近$ ϕ_c $的耗散过程的关键因素。
We study the impact between a plate and a drop of non-colloidal solid particles suspended in a Newtonian liquid, with a specific attention to the case when the particle volume fraction, $ϕ$, is close to - or even exceeds - the critical volume fraction, $ϕ_c$, at which the steady effective viscosity of the suspension diverges. We use a specific concentration protocol together with an accurate determination of $ϕ$ for each drop and we measure the deformation $β$ for different liquid viscosities, impact velocities and particle sizes. At low volume fractions, $β$ is found to follow closely an effective Newtonian behavior, which we determine by documenting the low deformation limit for a highly viscous Newtonian drop and characterizing the effective shear viscosity of our suspensions. By contrast, whereas the effective Newtonian approach predicts that $β$ vanishes at $ϕ_c$, a finite deformation is observed for $ϕ>ϕ_c$. This finite deformation remains controlled by the suspending liquid viscosity and increases with increasing particle size, which suggests that the dilatancy of the particle phase is a key factor of the dissipation process close to and above $ϕ_c$.
