Exploring the modulation of travelling surface acoustic waves on a double-point driven vibrating plate

Po-Wei Lee^1*, Yu-Chieh Lu¹, Pi-Hui Tuan¹

¹Department of physics, National Chung Cheng University, Chiayi, Taiwan

* Presenter:Po-Wei Lee, email:a7882909@gmail.com

The structure of sound is invisible since the wavelength of sound have a significant difference from visible light. Fortunately, by using specific methods, the structure of sound can be indirectly visualized via proper media. The so-called sound visualization can be traced back to Chladni who overlaid fine sand on a vibrating metal plate to manifest the attractive sound patterns corresponding to the standing-wave vibrating mode structures excited via a violin bow. Nowadays, by combining the formation mechanism for the standing-wave patterns with the designed algorithm, some research groups have successfully achieved the on-track navigation of particles on the vibrating plate. In addition to the standing-wave vibrating modes, the travelling-type surface acoustic waves (SAWs) which can transfer linear momentum to particles more straightforwardly can be possibly created under specific excitation conditions. In this work, we explore the generation and modulation of travelling SAWs by using a double-point driven vibrating plate. After using a primary oscillator to excite the brass plate to form the travelling SAW on the plate surface, the influences on the vibrating modes by introducing an additional point excitation via a control oscillator with different driving amplitudes are further examined. By analyzing the velocity fields for the moving particles under different double-point excitation conditions, it is confirmed that both the detailed structure and the particle flow direction corresponding to the travelling SAW can be continuously modulated by changing the amplitude ratio between the primary and control oscillators.

Keywords: Travelling surface acoustic waves, Vibrating plate, Sound visualization, Particle manipulation