Effects of tunable stiffness on the hydrodynamics and flow features of a passive pitching panel

Three-dimensional numerical simulations are carried out to study the hydrodynamic performance and flow features of a bio-inspired underwater propulsor. The propulsor is constituted by passive pitching panel. leading edge panel prescribed under periodic heaving motion while pitches passively due employing stiffness-lumped torsional spring at edge. Effects stiffness have been put emphases on. A real-time tunable strategy presented employed in study. We first effects on hydrodynamics using series constant then we cosinusoidal curve based waveforms, which phase difference (φ) between profile oscillation as well fluctuation amplitude (Gk) investigated, respectively. beneficial for propulsion efficiency further applied cases with different amplitudes. high-fidelity immersed boundary method direct simulation (DNS) solver acquire fluid dynamics simulate flow. solved coupling DNS Euler rigid body dynamic equation. Results show that cases, generates sinusoidal-like motion, certain range, flexibility could benefit holding some extent enhance thrust. For it found both mean thrust propulsive improved when change in-phase (φ=0°). largest φ=120°. wake shows φ=120° case, each cycle pair elongated twisted vortex tubes, tubes interconnected other induces unprofitable interactions. While φ=0° case round closed loops separated directly after they detached from thus avoided (all profile) all three tested (Gk=0.25G0,0.5G0,0.75G0) acquired enhancement Gk=0.5G0 Gk=0.75G0 had Wake profiles entire may not be formed Gk small larger affect arrangement generate results motions variable oscillating amplitudes (A∗) altering (φ=0°,Gk=0.5G0) improves range A∗ (0.4≤A∗≤0.8). this paper demonstrated potential design propulsors vehicles pursue higher performance.