论文标题
Ultraslow定居于摩擦粘粉的动力学
Ultraslow settling kinetics of frictional cohesive powders
论文作者
论文摘要
使用离散的元素方法模拟，我们表明，在压力压缩压缩下的摩擦粘性颗粒的沉降表现出强大的历史依赖性和缓慢的动力学，而这些动力学对于缺乏凝聚力或摩擦的晶粒而言不存在。从以稀释状态开始制备的系统，然后将压力升至一个小的正值$ p _ {\ rm final} $，在一个时间内$τ_{\ rm坡道} $在包装分数下定居，由逆量化率定律给出，$ ϕ _ {\ rm settled}（\ rm settled}（\ rm settle}）（ settled}（\ infty） + a/[1 + b \ ln（1 +τ_ {\ rm斜坡}/τ_ {\ rm slow}）] $。该定律类似于从非共晶粒上获得的经典敲击实验获得的定律，但至关重要的是，$τ_{\ rm slow} $是由结构空隙稳定的慢动力学设置的，而不是散装致密化的速度更快的动力学。我们制定了一种动力学的自由流量理论，该理论可以预测此$ ϕ _ {\ rm settled}（τ_ {\ rm lamp}）$，其中$ ϕ _ {\ rm settled}（\ rm settled}（\ infty}（\ infty）= ϕ _ {\ rm alp} $和$ alp} $和$ alp} $ _ = 0） ϕ _ {\ rm alp} $，其中$ ϕ _ {\ rm alp} \ equiv .135 $是````粘合松散的填料''，liu \ textit {et et al。} [et et al。} [e et et al。} [ \ textbf {13}，421（2017）]。
Using discrete element method simulations, we show that the settling of frictional cohesive grains under ramped-pressure compression exhibits strong history dependence and slow dynamics that are not present for grains that lack either cohesion or friction. Systems prepared by beginning with a dilute state and then ramping the pressure to a small positive value $P_{\rm final}$ over a time $τ_{\rm ramp}$ settle at packing fractions given by an inverse-logarithmic rate law, $ϕ_{\rm settled}(τ_{\rm ramp}) = ϕ_{\rm settled}(\infty) + A/[1 + B\ln(1 + τ_{\rm ramp}/τ_{\rm slow})]$. This law is analogous to the one obtained from classical tapping experiments on noncohesive grains, but crucially different in that $τ_{\rm slow}$ is set by the slow dynamics of structural void stabilization rather than the faster dynamics of bulk densification. We formulate a kinetic free-void-volume theory that predicts this $ϕ_{\rm settled}(τ_{\rm ramp})$, with $ϕ_{\rm settled}(\infty) = ϕ_{\rm ALP}$ and $A = ϕ_{\rm settled}(0) - ϕ_{\rm ALP}$, where $ϕ_{\rm ALP} \equiv .135$ is the ``adhesive loose packing'' fraction found by Liu \textit{et al.} [W.\ Liu, Y.\ Jin, S. Chen, H.\ A.\ Makse and S.\ Li, \textit{Soft Matt.} \textbf{13}, 421 (2017)].
