发表机构
KTH – Royal Institute of Technology; Politecnico di Torino; Lund University（皇家理工学院; 都灵理工大学; 隆德大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过二维离散元模拟发现，滚动摩擦通过降低堵塞堆积分数将连续剪切增稠转变为不连续剪切增稠，并揭示了其对颗粒转动运动学的独特影响。
AI 中文摘要
滑动摩擦降低了稠密悬浮液的堵塞堆积分数，并且在应力激活时驱动非惯性剪切增稠。额外的滚动阻力进一步降低了堵塞堆积分数，并可代表颗粒粗糙度或棱角性的影响。在接近堵塞时，它如何改变颗粒运动仍不清楚。使用应力控制的二维离散元模拟，我们将仅滑动摩擦的悬浮液与具有均匀或表面变化滚动摩擦的系统进行了比较。在固定的堆积分数下，添加滚动摩擦将连续剪切增稠转变为不连续剪切增稠。然而，在与应力相关的堵塞点相同距离处，即Δφ=φ-φ_m(σ)，流动曲线几乎重合，表明流变效应主要源于φ_m的移动。在此重合的指导下，我们比较了在匹配Δφ的高应力增稠状态下颗粒运动学，揭示了被相似整体响应所隐藏的差异。平动速度相关性延伸超过几个颗粒直径，而转动相关性保持局部性。滚动摩擦促进接触处的同向旋转，取代了强烈的反向旋转，并抑制了相对于平动涨落的转动涨落。然而，在每种情况下，转动在接近堵塞时变得越来越重要。具有表面变化滚动摩擦的悬浮液遵循均匀系统（μ_r≈0.3）的行为，因为在接触处采样的系数远低于表面平均值（此处μ_r≈0.5）。因此，Δφ在很大程度上组织了剪切增稠流变学，但并未组织颗粒运动学。颗粒运动学保留了滚动约束的独特特征，在使用滚动摩擦模拟粗糙或棱角颗粒时必须考虑这些特征。
英文摘要
Sliding friction lowers the jamming packing fraction of dense suspensions and, when activated by stress, drives non-inertial shear thickening. Additional rolling resistance lowers the jamming packing fraction further and can represent effects of particle roughness or angularity. How it changes particle motion on the approach to jamming remains unclear. Using stress-controlled two-dimensional discrete-element simulations, we compare a sliding-only suspension with systems having either uniform or surface-varying rolling friction. At fixed packing fraction, adding rolling friction changes continuous shear thickening into discontinuous shear thickening. At the same distance from the stress-dependent jamming point, $Δϕ=ϕ-ϕ_m(σ)$, however, the flow curves nearly collapse, showing that the rheological effect arises largely from the shift in $ϕ_m$. Guided by this collapse, we compare particle kinematics in the high-stress thickened state at matched $Δϕ$, revealing differences hidden by the similar bulk response. Translational velocity correlations extend over several particle diameters, whereas rotational correlations remain local. Rolling friction promotes co-rotation at contact in place of strong counter-rotation and suppresses rotational relative to translational fluctuations. Rotation nevertheless becomes increasingly important near jamming in every case. The suspension with surface-varying rolling friction follows the behavior of a uniform system with $μ_r\approx0.3$ because the coefficients sampled at contacts lie well below the surface average value, here $μ_r\approx0.5$. Thus, $Δϕ$ largely organizes the shear-thickening rheology, but not the particle kinematics. These retain a distinct signature of the rolling constraint that must be considered when rolling friction is used to model rough or angular particles.
