The influence of left and right inclination angles on the self-transport of lubricating oil in 3D capillary ratchet structures

Purpose Taking the Araucaria leaf-inspired surface (ALIS) structure as the research object, this study aims to investigate the effect and mechanism of the ratchet inclination angle on the directional transportation of lubricating oil. Design/methodology/approach This study is conducted by combining computational fluid dynamics (CFD) simulation with experimental verification. First, the reliability of the simulation results is verified through comparative analysis of experiments and CFD numerical simulations. Subsequently, the inclination angles of the ratchet microstructures on both sides of the ALIS are adjusted at 5° intervals, and the self-transportation effects of lubricating oil under the three-column and four-column structures are explored respectively. Findings This study finds that in the three-column structure, when the inclination angle is 10°, the transportation height of lubricating oil on both sides shows a trend of first increasing and then decreasing. In the four-column structure, the inner and outer microstructures reach the peak transportation height at inclination angles of 5°/10° and 10°/15°, respectively, and both sides present a trend of first increasing and then decreasing. Comprehensively, 10°–15° is the optimal inclination angle range, under which the lubricating oil rising effect is the best. Originality/value This study clarifies the influence law of the ratchet inclination angle on the lubricating oil transportation, and provides theoretical basis and data support for the optimization of microstructure design and the improvement of the directional transportation performance of lubricating oil.