Cyclones and attractive streaming generated by acoustical vortices.

Area of Science:

• Acoustics and Fluid Dynamics
• Acoustic Manipulation
• Vortex Dynamics

Background:

• Acoustical and optical vortices are known for particle manipulation via radiation pressure.
• Controlling fluid flow with acoustic fields is an area of active research.

Purpose of the Study:

• To demonstrate that acoustical vortices can induce axial vortical flow.
• To show that the topology of this flow can be controlled by acoustic beam properties.
• To investigate the generation of "attractive streaming" in confined geometries.

Main Methods:

• Generation of acoustical vortices with controllable beam properties.
• Observation and analysis of induced axial vortical flow.
• Experimental setup in confined geometry to study streaming effects.

Main Results:

• Acoustical vortices were shown to induce axial vortical flow, mimicking cyclones.
• The flow topology was successfully controlled by modifying the acoustical beam.
• "Attractive streaming" directed towards the transducer was generated in confined spaces.

Conclusions:

• Acoustical vortices offer a novel method for inducing and controlling vortical fluid flow.
• The ability to control flow topology opens new avenues for contactless fluid manipulation.
• The generation of attractive streaming has significant implications for microfluidics and acoustic manipulation technologies.