Numerical Verification of Generation of Ultrasound-Driven Bent Flow by Centripetal and Tangential Body Force Field

We propose a method of generating midair acoustic streaming traveling along a curve by combining a central acceleration field with a tangential one by ultrasound emissions from multiple phased arrays of ultrasound transducers. Via numerical experiments, we confirmed, using a hypothetical acceleration field, that a centripetal force contributed to the steady formation of a narrow curved flow. We also demonstrated that a curved flow (0.4 m radius semicircle) could be generated by the phased arrays emitting both centripetal and tangential acceleration field in their possible arrangements, both numerically and experimentally. Half of the arrays generated tangential force field parallel to the given beam trajectory and the others generated centripetal force field that penetrated the center of the array. Although currently generated flows being short in spatial range, such curved flows can potentially increase the spatial flexibility of applications, by circumventing obstacles in the environment, for example.