arXiv subjects

Eric E. Handy-Cardenas

Publications and source records attributed to Eric E. Handy-Cardenas.

2 recordsLinked to original sources

arXiv2026

Vibrissa inspired geometries enhance sensitivity of wake-induced vibrations

We report on experiments designed to characterize the vortex-induced vibration (VIV) and wake-induced vibration (WIV) experienced by bluff bodies immersed in both steady and unsteady flows. Using a real-time Cyber-Physical System (CPS) we systematically prescribe the virtual mass, spring constant, and damping of elastically mounted models. This allows us to characterize the forces and displacements of the free vibration of a circular cylinder, elliptical cylinder, and a seal whisker inspired vibrissa model with undulating elliptical geometry. In a free flow, the circular cylinder exhibits high VIV, while the reduced aspect ratio objects have minimal vibration across all structural frequencies. When a flow disturbance of a pitching and heaving hydrofoil is introduced, the reduced aspect ratio objects are excited by WIV with highest amplitude oscillations occurring when structural frequency of the test object matches wake frequency of the upstream foil. To further understand the benefits of an undulated geometry over a classic elliptical cylinder, we assess the nonlinear fluid damping experienced by each test object by comparing experimental data to quadratic drag and Van der Pol damping models. Our results show that the amplitude dependent Van der Pol damping model better describes the physical system for both test objects by capturing the suppression of large amplitude WIV, but recovering small amplitude VIV. However, the strength of the fitted Van der Pol damping coefficient is greater for the elliptical cylinder than the vibrissa. We find the vibrissa experiences lower damping than the elliptical cylinder across all tested structural frequencies, indicating how the vibrissa geometry may serve as a higher sensitivity sensor.

physics.flu-dyn↗

arXiv2024

Optimal Kinematics for Energy Harvesting Using Favorable Wake-Foil Interactions in Tandem Oscillating Hydrofoils

The energy harvesting performance of a pair of oscillating hydrofoil turbines in tandem configuration is experimentally studied to determine the optimal kinematics of the array. By characterizing interactions between the wake produced by the leading foil and the trailing foil, the kinematic configuration required to maximize array power extraction is determined. This is done by prescribing leading foil kinematics that produce specific wake regimes, identified by the maximum effective angle of attack parameter. The kinematics of the trailing foil are allowed to vary significantly from those of the leading foil. The heave and pitch amplitude, inter-foil phase, and foil separation of the trailing foil are varied within each wake regime and the system performance is evaluated. The power extracted by each foil over an oscillation cycle is measured through force and torque measurements. Wake-foil interactions that yield improvements in trailing foil performance are analyzed with time-resolved Particle Image Velocimetry. Constructive and destructive wake-foil interactions are compared, and it was determined that trailing foil performance could be improved by either avoiding interactions with wake vortices or by interacting directly with them. The latter configuration takes advantage of the wake vortex, and does not see power loss during the oscillation cycle. System power from the two foils is maximized when the leading foil is operated at an intermediate maximum angle of attack range, and when the trailing foil avoids collisions with wake vortices. This optimal array configuration sees both foils operating with different kinematics compared to the optimal kinematics for a single oscillating foil.

physics.flu-dyn↗