Rotational mechanical effects of sound
The exploratory studies on sound-matter interaction are to date one of the most promising directions as fundamental
research which can be used practically in rheology, medical imaging and other contactless manipulations. So far only
acoustic radiation force is used in applications. The study of rotational mechanical effects of sound actually remains in its
infancy and expected application potential invites a better understanding of acoustic radiation torques and further
fundamental experimental investigations. With the aim at going beyond the state-of-the art, the research project proposes to
explore experimentally new facets of the rotational mechanical effects of sound based on the use of acoustic vortex beams,
which are characterized by a helical wavefront bearing on-axis phase singularity. Indeed, depending on the specific wavematter
interaction, acoustic vortex beams can induce various rotational mechanical effects, such as angular displacements,
spinning or orbiting motions. Our approach will first consist to study acoustic radiation torque effects that do not rely on
sound-absorption, which corresponds to a sound-matter interaction regime barely explored experimentally. Also, we will
unveil experimentally the existence of recently predicted a spin contribution to the total angular momentum of acoustic vortex
beams. For these purposes, we will firstly develop a toolbox allowing versatile acoustic vortex beam shaping in the ultrasonic
regime owing to 3D printing technologies. Then, by using obtained vortex beams and appropriately designed sound-matter
interaction schemes, we will detect and monitor quantitatively the sought-after rotational mechanical effects. By addressing
original and timely scientific challenges on experimental grounds, the project will bring new knowledge in the field of acoustic
angular momenta and set a new state-of-the-art for acoustic contactless manipulations.