Influence of wettability on drag reduction performance during turbulent flow

The wettability of lubricant oil produces a velocity slip at the water–lubricant oil interface when the lubricant oil contacts the rectangular microgroove, leading to a reduction in the friction resistance at the boundary wall. However, lubricant oil is highly susceptible to changes in external shear force and can escape from the rectangular microgroove, degrading its slippery properties. This study investigated the influence of wettability and structure width on the stability and drag reduction performance of lubricant oil via simulation. The results indicated that lubricant oil stability is related to wettability and structural width. The lubricant oil remained stable at contact angles of 1° and 150° and a width of 0.4 mm. Based on slip velocity, the maximum drag reduction at a width of 0.6 mm in a turbulent environment was 13.4%. Our findings could provide valuable insights into surface design using lubricant oil, helping researchers avoid detrimental designs and enhance sustainable drag reduction performance.