Trapping and manipulation of a small object in the space between two pipes placed to the counter direction

A small object can be trapped in the space between two pipes which are placed to the counter direction and radiated traveling acoustic waves from the pipe ends. In the study, two pipes vibrating in axisymmetric flexural damped traveling wave to generate acoustic flow in the pipe inside are used. The flow propagates in the pipe inside and is radiated for traveling acoustic waves from the pipe end. The pipe made of polycarbonate is used for ultrasonic transmission pipe and two piezo-ceramic annular plates are adhered at the each pipe end for exciting the vibration modes. The first radial vibration mode of the annular plate is used and its resonance frequency is about 59 kHz. When the two vibrators are driven in opposite phase, a small object can be trapped at intermediate point in the space between two pipe ends. The gap of the space is about 10 mm. The trapping object can be shifted its position corresponding to the phase difference of the two driving voltages. That is, the object can be moved on non-conta...