Numerical study of the oscillatory boundary layer over wall-mounted flexible filaments

This study explores the flow-structure interaction between the oscillatory boundary layer flow and an array of wall-mounted flexible filaments using a penalty-immersed boundary method. The key finding is that the presence of filaments lifts the boundary layer by the average filament height. A partial slip boundary condition with a complex-valued slip length is introduced to quantify the velocity-velocity gradient relation. It indicates the slip length reaches a stable value at the upper edge of the filaments. This study provides insight into modeling the effective boundary condition of the filament-attached wall.