The acoustic vortex wave has exhibited high-potential applications such as communication. In this work, the authors propose an efficient method for quantitatively measuring the topological charge of an acoustic vortex through two kinds of annular apertures: an annular triangle aperture and an annular ellipse aperture. It is found that the characteristics of the diffraction pattern in the far-field are well related with the shape of apertures and the topological charges of the acoustic vortex wave. Therefore, the topological charge of acoustic vortex beams can be determined from the diffraction patterns, which provide an effective method for measuring the topological charge of acoustic vortex beams.
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http://dx.doi.org/10.1121/10.0001521 | DOI Listing |
JASA Express Lett
December 2024
Applied Research Laboratories, The University of Texas at Austin, Austin, Texas 78766-9767, USA.
Analytical solutions for acoustic vortex beams radiated by sources with uniform circular amplitude distributions are derived in the paraxial approximation. Evaluation of the Fresnel diffraction integral in the far field of an unfocused source and in the focal plane of a focused source leads to solutions in terms of an infinite series of Bessel functions for orbital numbers ℓ>-2. These solutions are reduced to closed forms for 0≤ℓ≤4, which correspond to orbital numbers commonly used in experiments.
View Article and Find Full Text PDFJASA Express Lett
December 2024
Royal Canadian Navy, Esquimalt, British Colombia, V9a,
Damage and fouling to a marine propeller can alter underwater noise levels through numerous mechanisms, but there are very few studies where clean propellers are compared to those with realistic levels of damage or fouling. This study presents acoustic data combined with underwater camera footage for a vessel fitted with three propellers: clean, damaged, and fouled. The results show that the fouled propeller is quieter than the clean one due to it reducing the levels of tip vortex cavitation.
View Article and Find Full Text PDFAdv Mater Technol
September 2024
Fralin Biomedical Research Institute, Virginia Polytechnic Institute and State University, Roanoke, VA, 24016, USA.
Tweezers based on optical, electric, magnetic, and acoustic fields have shown great potential for contactless object manipulation. However, current tweezers designed for manipulating millimeter-sized objects such as droplets, particles, and small animals, exhibit limitations in translation resolution, range, and path complexity. Here, we introduce a novel acoustic vortex tweezers system, which leverages a unique airborne acoustic vortex end effector integrated with a three degree-of-freedom (DoF) linear motion stage, for enabling contactless, multi-mode, programmable manipulation of millimeter-sized objects.
View Article and Find Full Text PDFBiomimetics (Basel)
November 2024
Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
Dolphin swimming has been a captivating subject, yet the dorsal fin's hydrodynamics remain underexplored. In this study, we conducted three-dimensional simulations of flow around a wall-mounted dolphin dorsal fin derived from a real dolphin scan. The NEK5000 (spectral element method) was employed with a second-order hex20 mesh to ensure high simulation accuracy and efficiency.
View Article and Find Full Text PDFSci Adv
November 2024
Department of Dermatology, Xiangya Hospital, Central South University, Changsha 410008, China.
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