Plug Flow and Cavitation in Rough Lubricated Contacts: Molecular Dynamics of Single- vs. Two-Component Fluids
Abstract
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.
Related
- Quartz Crystal Microbalance impedance of discrete adsorbates with lubricated contact
- Surface morphology and shear effect on lubricated granular system
- Anisotropic Nanoparticle Rejamming Triggers Thermodynamic Cavitation in Elastomer Nanocomposites
- Meso-scale modeling of cohesive cavitation in polymer networks
- Shear induced cavitation in radially expanding, chemically equilibrating QGP
BibTeX
@misc{agarwal2026plug,
title = {{Plug Flow and Cavitation in Rough Lubricated Contacts: Molecular Dynamics of Single- vs. Two-Component Fluids}},
author = {Shubham Agarwal and Martin H. Müser},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.15008},
eprint = {2607.15008},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.15008},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Plug Flow and Cavitation in Rough Lubricated Contacts: Molecular Dynamics of Single- vs. Two-Component Fluids
AU - Shubham Agarwal
AU - Martin H. Müser
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2607.15008
UR - https://arxiv.org/abs/2607.15008
AB - 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.
ER -