粗糙润滑接触中的塞流与空化：单组分与双组分流体的分子动力学
Plug Flow and Cavitation in Rough Lubricated Contacts: Molecular Dynamics of Single- vs. Two-Component Fluids
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中文总结 AI 辅助
研究粗糙润滑接触中塞流与空化，通过非平衡分子动力学模拟，在相同几何条件下比较水、正十二烷及双流体润滑，发现混合润滑剂摩擦和材料转移最低，能保持塞流，还揭示了单组分润滑剂相关特性及空化机制。
中文摘要 AI 辅助
我们展示了在代表边界润滑和混合润滑条件下，粗糙、可变形表面间润滑滑动的非平衡分子动力学模拟。一个目的是缩小光滑界面的高度理想化模拟与真实、粗糙、承载接触之间的差距。另一个目的是确定溶剂化的亲水 - 疏水聚合物刷界面所报道的双流体润滑的有利摩擦学特性在无刷的粗糙接触中是否也能实现。为此，我们在相同几何条件下比较了水、与水在环境条件下具有相似平衡粘度的烃（正十二烷）以及不混溶的双流体润滑。对于单组分润滑剂，模拟再现了既定趋势：水比正十二烷表现出更强的速度依赖性但承载能力降低。此外，模拟表明强约束和大高度梯度的组合会在微凸体碰撞后导致塞流和空化。对于水这样的高表面张力液体，空化提供了一种在远超腔体尺寸的尺度上可观测到的突然剪应力释放机制。混合润滑剂表现出最低的摩擦和材料转移，同时在最低滑动速度下保持塞流。它也是唯一形成折叠唇的系统，在高速时偶尔会发展成瞬态磨损颗粒。
英文摘要
We present non-equilibrium molecular dynamics simulations of lubricated sliding between rough, deformable surfaces under conditions representative of mixed lubrication. One aim is to reduce the gap between highly idealized simulations of smooth interfaces and real, rough, load-bearing contacts. Another aim is to determine whether favorable tribological properties of two-fluid lubrication reported for solvated hydrophilic-hydrophobic polymer-brush interfaces can also be realized in rough contacts without brushes. To this end, we compare aqueous (water), hydrocarbon (n-dodecane), and immiscible two-fluid lubrication under identical geometric conditions representing randomly rough surfaces. For the single-component lubricants, the simulations reproduce established trends: water shows stronger speed dependence but reduced load-bearing capacity than n-dodecane, despite their similar ambient viscosities. Beyond this expected behavior, the simulations reveal that the combination of strong confinement and large height gradients can cause plug flow and thereby cavitation after asperity collisions. For a high-surface-tension liquid like water, cavitation leads to an abrupt shear-stress release on scales much exceeding the size of the cavity. Since plug motion only weakens with single-component lubricants at low speeds, the two-fluid lubricant can only leverage its potential advantages at low sliding velocities. It is also the only system in which folding lips form, occasionally developing into transient, detached clusters at high speeds.
发表机构
- Materials Science and Engineering, Campus C6.3, Saarbrücken, 66123, Germany（材料科学与工程）
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