TY - JOUR AU - Català, Pau AU - Marc, Vallbé-Mumbrú AU - Pérez-Ràfols, Francesc PY - 2025 TI - Roughness induced variation as a new mechanism for hydrodynamic lubrication between parallel surfaces JO - Friction SN - 2223-7690 SP - 9441015 VL - 13 IS - 4 AB - This work proposes a new lift mechanism capable of explaining the hydrodynamic lift observed in real mechanical face seals with parallel surfaces. While it is well established that roughness is a key factor inducing such lift, its effect is commonly explained in the form of micro-wedges and asperity-level cavitation. The novelty of this work is to consider roughness induced random variability in the flow restriction, which induces effective wedges. First, a dedicated stochastic two-scale model is developed and used to demonstrate the proposed new mechanism in a case study. We demonstrate that the described new mechanism acts at scales comparable to the macroscopic size of the seal, much larger than the commonly considered micro-wedges. Afterwards, the limitations for this new proposed mechanism are discussed. UR - https://doi.org/10.26599/FRICT.2025.9441015 DO - 10.26599/FRICT.2025.9441015