Cui Xianxian, Chen Dengke, Chen Huawei
School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
School of Transportation, Ludong University, Yantai 264025, Shandong Province, China.
ACS Omega. 2023 Feb 20;8(9):8569-8581. doi: 10.1021/acsomega.2c07729. eCollection 2023 Mar 7.
Shark skin-inspired riblets have represented the tremendous potential for drag reduction (DR) and antifouling in submarine, ship, and so on. Most studies simplified the complex denticle embedded in the shark skin into the single-stage riblet with uniform parameters, ignoring the influence of riblet height gradient and material deformation on DR and antifouling. In the present study, flexible multistage gradient riblets (MSGRs) with varied heights were proposed, and their DR and antifouling effects were investigated by the experiment and numerical simulation. The experimental results showed that the maximum DR rate of flexible MSGRs with an elastic modulus of 4.592 MPa could reach 16.8% at a flow velocity of 0.5 m/s. Moreover, the dynamic adhesion measurement indicated a reduction by 69.6% of the adhesion area of on the flexible MSGR surface. The results identified that flexible MSGRs with low surface energy could generate steady high- and low-velocity streaks and alter the flow state of the fluid, thus lessening the average velocity gradient near the wall and the adhering selectivity of pollutants in riblet and achieving synergistic DR and efficient antifouling. Taken together, the proposed flexible MSGR surface holds promise for reducing surface friction and inhibiting particle attachment in engineering applications.
受鲨鱼皮启发的脊状结构在潜艇、船舶等方面展现出了巨大的减阻和防污潜力。大多数研究将嵌入鲨鱼皮的复杂小齿简化为具有统一参数的单级脊状结构，而忽略了脊状高度梯度和材料变形对减阻和防污的影响。在本研究中，提出了具有不同高度的柔性多级梯度脊状结构（MSGRs），并通过实验和数值模拟研究了它们的减阻和防污效果。实验结果表明，弹性模量为4.592 MPa的柔性MSGRs在流速为0.5 m/s时的最大减阻率可达16.8%。此外，动态附着力测量表明，在柔性MSGR表面上的附着力面积减少了69.6%。结果表明，具有低表面能的柔性MSGRs可以产生稳定的高速和低速条纹，改变流体的流动状态，从而减小壁面附近的平均速度梯度以及污染物在脊状结构中的附着选择性，实现协同减阻和高效防污。综上所述，所提出的柔性MSGR表面在工程应用中具有降低表面摩擦和抑制颗粒附着的潜力。
