| 摘要 |
An acoustic standing wave is established in a fluid medium with a varying energy density in its nodal planes. Particles in the fluid medium responsive to the acoustic energy accumulate at these nodal planes and by the action of the variations of energy density in conjunction with the fluid viscous forces and/or field forces acting in the direction of the nodal planes, the movement of the particles held at these planes can be controlled. The adverse effects of attenuation of the acoustic beams producing the standing wave are reduced in this system, because any streaming due to imbalance of the acoustic forces forming the standing wave does not act in the direction in which the movement of the particles can be controlled. |
