Experimental Investigation of Drag Reduction Properties of Bioinspired Interfaces by Modal Decomposition and Rotary Rheometer

The rapid advancement of the ship transportation industry has intensified the need for enhanced drag reduction and speed optimization in marine vessels and underwater vehicles. In this context, boundary layer control technology has emerged as a pivotal area of research due to its potential to substantially mitigate hydrodynamic resistance. To investigate this, particle image velocimetry was utilized in a recirculating water tunnel to analyze flow fields over smooth and biomimetic textured surfaces. Modal decomposition techniques (Dynamic Mode Decomposition, Empirical Mode Decomposition) and wavelet transform were applied to characterize flow dynamics. The results demonstrate that biomimetic microstructures disrupt the self-sustaining mechanisms of streamwise vortices and near-wall vortical structures, effectively attenuating flow separation. Furthermore, the energy associated with large-scale coherent structures is redistributed to smaller-scale, high-frequency turbulent motions, while momentum transport in the wall-normal direction is inhibited. These insights offer a novel framework for analyzing flow behavior over biomimetic drag-reduction surfaces and enable the simplification of intricate fluid systems, thereby reducing computational demands in hydrodynamic modeling.