Theoretical modeling and experimental characterization of boundary slip on aluminum surface with small-amplitude roughness

Abstract

Boundary slip has a significant influence on micro/nano-scale flow and its quantitative description has become a prerequisite for design and fabrication of micro/nano-scale fluid systems. In this research, a physical model for boundary slip on aluminum surface with small-amplitude roughness was proposed, which considered the synergistic effects of solid-liquid interface parameters such as fluid properties, wettability and roughness. Besides, the boundary slip experiments were carried out using atomic force microscope (AFM) method to verify model accuracy. According to experimental results, the roughness (Ra) values of different aluminum surfaces were 0.47 nm, 1.16 nm, 1.94 nm, 2.63 nm and 3.18 nm, respectively. Correspondingly, the slip lengths were 23.7 nm, 20.3 nm, 18.5 nm, 15.9 nm and 12.7 nm, respectively. It was found the proposed slip model was in good agreement with experimental results, which could describe boundary slip on rough surface more accurately. This research could provide beneficial guidance for understanding of physical mechanism and quantitative description of boundary slip on solid surface with small-amplitude roughness.