Fluidization and wall slip of soft glassy materials by controlled surface roughness

Area of Science:

• Fluid Dynamics
• Microfluidics
• Soft Matter Physics

Background:

• Concentrated emulsions exhibit complex flow behaviors in confined geometries.
• Microfluidic devices offer precise control over fluid environments.
• Surface topography can significantly influence fluid dynamics and material transport.

Purpose of the Study:

• To investigate the flow dynamics of concentrated emulsions in microfluidic channels with patterned walls.
• To establish a predictive model for roughness-induced fluidization.
• To explore applications in droplet manipulation and other jammed systems.

Main Methods:

• Experimental study of concentrated emulsions flowing through microfluidic channels.
• Microchannels featured patterned walls with micron-size grooves perpendicular to flow.
• Numerical simulations to analyze fluidization mechanisms and plastic rearrangements.

Main Results:

• A scaling law was identified, correlating fluidization with groove density.
• Fluidization was shown to be predictable and quantitatively controllable via groove patterning.
• Droplet trapping and release mechanisms were elucidated.
• Simulations confirmed the link between fluidization and plastic rearrangement distribution.

Conclusions:

• Microchannel wall patterning provides effective control over concentrated emulsion fluidization.
• The derived scaling law enables quantitative prediction and regulation of fluidization.
• The findings have potential applications in droplet manipulation and managing other jammed materials.