Drag Reduction Characteristics of Bionic Structure Composed of Grooves and Mucous Membrane Acting on Turbulent Boundary Layer

The biological surface structure comprising fish scales and a mucous membrane exhibits good turbulent drag reduction ability. Based on this structure, a bionic frictional drag reduction model composed of a groovedstructure and mucous membrane was established herein, and its efficacy in reducing the resistance of aturbulent boundary layer was analyzed. Accordingly, the drag reduction performance of the bionic structurewas investigated through large eddy simulations. The results revealed that the mucous membrane was evenlydistributed on the groove wall through secretion, and effectively improved the drag reduction rate of thegroove wall. The bionic grooves and mucous membrane structure successfully inhibited the turbulent kineticenergy, turbulence intensity, and Reynolds stress. The grooved structure improved the shape of the Λ vortexstructure and the mucous membrane reduced the number of three-dimensional (3D) vortex structures.Furthermore, the streak structure near the bionic structure wall was reduced and its shape was regularized,which intuitively demonstrates the turbulence suppression ability of the proposed bionic structure.