Phononic-subsurface flow stabilization by subwavelength locally resonant metamaterials

Abstract The interactions between a solid surface and fluid flow underlie dynamical processes relevant to air, sea, land vehicle performance numerous other technologies. Key among these are unstable disturbances that contribute fundamental transformations in the field. Precise control of is possible by introducing phononic subsurface (PSub). This comprises locally attaching finite structure nominally perpendicular an elastic exposed flowing fluid. experiences ongoing excitation mode, or more than one traveling conjunction with mean flow. generates small deformations at trigger wave propagation within structure, away from reflecting end return fluid-structure interface back into By targeted tuning unit-cell finite-structure characteristics PSub, returning waves may be devised resonate reenter out phase, leading significant destructive interference continuously incoming near subsequently their attenuation over spatial extent region. entire mechanism passive, responsive, engineered offline without needing coupled simulations; only instability’s frequency, wavelength, overall modal must known. Disturbance stabilization wall-bounded transitional leads delay laminar-to-turbulent transition reduction skin-friction drag. Destabilization also alternatively designing PSub induce constructive interference, which beneficial for delaying separation enhancing chemical mixing combustion. In this paper, we present form resonant metamaterial, designed operate subwavelength regime hence being significantly shorter length compared phononic-crystal-based PSub. enabled utilizing sub-hybridization resonance. Using direct numerical simulations channel flows, both types PSubs investigated, controlled energetic influence on behavior demonstrated analyzed. We show PSub’s effect spatially localized as intended, rapidly diminishing streamwise its location subsurface.