ORE Seminar: Sounds, Signals, Spectra: Splash to Buzz

April 20, 3:30pm - 4:30pm
Mānoa Campus, Holmes Hall 247 & Zoom (see description for meeting ID and passcode)

Acoustics is an extensive inter-disciplinary research area that encompasses topics in diverse fields such as music, science and engineering. The areas of acoustic share a common core with respect to the governing equations for wave propagation in gaseous (air), liquid (water) or solid materials. Bubbles play an important role in sound generation in the ocean as well physical and biomedical acoustic applications. Recent experimental studies on acoustics of bubbles are presented. In air entrainment processes, unique acoustic signatures are associated with their oscillations. Drop impact on surfaces has been studied comprehensively as it has wide range of fundamental and practical implications. The splash, spreading and rebound have been investigated with respect to substrate interfaces with hydrophobic surfaces being of particular interest. Also the associated acoustics of the drop impact has only recently been explored in terms of air entrainment and substrate vibrations. Recent experimental results are presented for drop on drop impact and also the impact of hydrogel spheres on drops resting on hydrophobic surfaces. The initial rebound and subsequent jet break-up are shown in analysis of the signal’s amplitude and phase. Also discussed are biological acoustics with respect to the buzz of insect’s flapping wing sounds. The sounds of flapping wing insects are typically dominated by a fundamental with higher harmonics though the underlying structure and aero-acoustics beyond the frequency and amplitude are not well understood, especially for beetles. The aerodynamics and acoustics of invasive species of beetles are of interest in terms of fundamentals of flight and detection methods. Coconut Rhinoceros Beetle (Oryctes rhinoceros) and the Oriental Flower Beetle (Protaetia orientalis) have been studied during tethered flight with synchronized microphone array measurements and high speed video (1000-10,000 fps). Computational fluid dynamics simulations were performed using the unsteady compressible flow solver (CAESIM, Adaptive Research, Inc.) using a high resolution (TVD) methodology. Models of the wing flapping motion were accomplished using mesh deformation techniques with the flapping following from rotation with prescribed bending and coupled rotation and translation from the wing’s hinge position. This seminar will be given by Dr. John S. Allen, Associate Professor in the Mechanical Engineering Department. Zoom Meeting ID: 960 4654 5799, Meeting Passcode: OREseminar

Event Sponsor
Ocean and Resources Engineering, Mānoa Campus

More Information
(808) 956-7572, https://www.soest.hawaii.edu/ore/event/seminar_220420/

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