1. Three-dimensional analysis of hydrodynamic forces and power dissipation in shape-morphing cantilevers oscillating in viscous fluids.
- Author
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Ahsan, Syed N. and Aureli, Matteo
- Subjects
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WING-warping (Aerodynamics) , *FLUIDS , *FLUID-structure interaction - Abstract
Highlights • We study harmonic 3D oscillations of a shape-morphing cantilever in a viscous fluid. • The beam cross section deforms with prescribed periodic curvature during vibrations. • We use oscillatory Stokeslets methods to study lift, thrust, and power dissipation. • Hydrodynamic forces and power can be modulated by varying the imposed curvature. • Propulsion performance can be maximized for an optimal shape-morphing strategy. Graphical abstract Abstract In this paper, we investigate flexural vibrations of a thin sharp-edged cantilever beam submerged in a quiescent, Newtonian, incompressible, viscous fluid. We study the three-dimensional fluid–structure interaction problem in the presence of shape-morphing deformation of the beam cross section, imposed by specifying a periodic chordwise maximum curvature along the axis of the structure, coupled with the flexural motion of the beam occurring along a structural mode. This actuation strategy, resulting into anticlastic curvature for the beam, is investigated as a possible means to actively control fluid–structure interaction mechanisms by modifying the hydrodynamic interactions in the vicinity of the submerged structure. We focus on the linear vibration problem for the beam, whereby the fluid flow is well described by three-dimensional unsteady Stokes hydrodynamics. Using the hypothesis of imposed harmonic motion for the submerged structure, we solve the linear hydrodynamics problem in the frequency domain by employing a semianalytical method based on oscillating Stokeslets. The resulting integral equations are solved via a boundary element technique and our results are validated against findings from the literature. The efficacy of the proposed shape-morphing strategy on the propulsion performance is assessed by studying thrust production, lift forces, and hydrodynamic power dissipation for a range of prescribed dynamic and geometric conditions, including vibration frequency, amplitude of imposed chordwise curvature, and beam aspect ratio. Our results indicate that thrust forces and power dissipation can be simultaneously modulated via the shape-morphing strategy. We theoretically predict and numerically confirm the existence of extremal points that result into an optimal compromise between thrust forces and power dissipation. Such optimal solutions are of direct interest to the design of cantilever-based underwater biomimetic propulsion systems, where it is crucial to control and modulate oscillation quality factors, hydrodynamic forces, and power losses. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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