Degeneration of flow pattern in acousto-elastic flow through sharp-edge microchannels

Area of Science:

• Fluid Dynamics
• Non-Newtonian Rheology
• Acoustic Engineering

Background:

• Acoustic streaming (AS) is crucial for mixing and particle manipulation in Newtonian fluids.
• Biological and chemical solutions often exhibit non-Newtonian properties, limiting AS applications.
• Understanding AS in viscoelastic fluids is essential for advancing microfluidic technologies.

Purpose of the Study:

• To experimentally investigate acoustic streaming in viscoelastic fluids for the first time.
• To characterize the flow behavior of viscoelastic fluids under acoustic fields.
• To explore potential applications of acousto-elastic flow in microfluidics.

Main Methods:

• Introduction of polyethylene oxide (PEO) polymer to create viscoelastic fluids.
• Experimental study of acoustic streaming in microchannels.
• Quantitative analysis of flow patterns and characteristics.

Main Results:

• Viscoelastic fluids exhibit unique acousto-elastic flow with positive and negative modes.
• Mixing hysteresis observed at low flow rates in viscoelastic fluids.
• Flow pattern degeneration, including time fluctuation and reduced disturbance range, occurs at high flow rates.

Conclusions:

• Acousto-elastic flow in viscoelastic fluids presents distinct behaviors compared to Newtonian fluids.
• Positive mode enhances mixing in micromixers for viscoelastic fluids.
• Negative mode offers potential for particle/cell manipulation in viscoelastic biological fluids like saliva.