  In an ultrasonic field the region around a solid particle experiences small,
localised velocity, pressure, and thermal fluctuations that decay rapidly over
short length scales. Herein, we investigate the overlap of the rapidly decaying
fields between two silica particles in water in the case where the particles
are aligned with each other in the direction of the applied field. We explore
the velocity, pressure, temperature, and vorticity in the region of the
particles. We discuss the coupled particle effects in ultrasonic waves as
particles begin to agglomerate or become more concentrated. The analysis is
conducted in the long wavelength regime for particles of diameter 500 nm and
frequency 9.7 MHz.
