RT Journal Article
T1 Comparing analytically propulsion by pitching and heaving flexible foils near the first two natural modes
A1 Fernández-Feria, Ramón
K1 Deformaciones (Mecánica)
K1 Flexión (Mecánica)
AB An analytical formulation is provided that describes the first two natural modes of thefluid–structure interaction of an incompressible current with a pitching and heavingflexible plate. The objective is twofold: first, to present a general derivation of analyticalexpressions for the lift, moment and the flexural moments exerted by an inviscid flow ona pitching and heaving plate whose deformation is general enough that the coupling ofthe flexural moments with the structural equations allows solving analytically the first twonatural modes of the system; second, to analyse the propulsion performance of the foilwhen actuated near the first two natural frequencies. For the second purpose, one alsoneeds the thrust force generated through the motion and the general deformation of thefoil considered, which is analytically derived using the linearized vortex impulse theory,extending and systematizing previous works. The analytical expressions, once viscouseffects are taken into consideration through nonlinear transverse damping and offset dragcoefficients, are compared with small-amplitude available experimental data, discussingtheir limitations. It is found that low stiffness pitching and heaving are quite different,with a pitching flexible foil only generating thrust near the second resonant frequency,whereas heaving always generates thrust, with the maximum slightly below the secondnatural frequency. Maximum thrust for large stiffness pitching is around the first naturalfrequency. The maximum efficiency occurs at frequencies close to the first natural modeif the foil is sufficiently rigid, but it is not related to the natural frequencies as the rigiditydecreases.
PB Cambridge University Press
YR 2025
FD 2025
LK https://hdl.handle.net/10630/39542
UL https://hdl.handle.net/10630/39542
LA eng
NO Fernandez-Feria, R. (2025). Comparing analytically propulsion by pitching and heaving flexible foils near the first two natural modes. Journal of Fluid Mechanics, 1015, A35. doi:10.1017/jfm.2025.10390
NO Funding for open access charge: Universidad de Málaga
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 20 ene 2026