Prof. Steven Cummer / Wavefront Control with Acoustic Metamaterials: Concepts and Applications скачать в хорошем качестве

Prof. Steven Cummer / Wavefront Control with Acoustic Metamaterials: Concepts and Applications

TII Metamaterials and Applications Seminar 2021 – Steven Cummer – Duke University Acoustic metamaterials use structure, rather than the intrinsic properties of materials, to manipulate and control sound waves in ways that are challenging or impossible with conventional materials. One of the main paradigms behind acoustic metamaterial design is wavefront control, in which known incident wavefronts are to be converted into desired reflected or transmitted wavefronts. In this way, incident acoustic energy can be arbitrarily steered, split, focused, or even given orbital angular momentum. Such wave manipulation can often be accomplished in a relatively thin acoustic metamaterial structure (also called a metasurface), making physical realization simpler. This presentation will describe some of our group’s recent research in the area of acoustic wavefront control. This will include a short summary of our metasurface research using phase-control elements and diffraction, followed by more recent work on so-called perfect metasurfaces, in which acoustic structures are designed to control the local surface impedance and thereby create more efficient transmission and reflection. The last part will describe our applications of these concepts to create ultrasonic acoustic fields in water to control fluid force, trapping, and streaming at small spatial scales.