Peristaltic Elastic Instability in an Inflated Cylindrical Channel

Area of Science:

• Soft Matter Physics
• Fluid Dynamics
• Materials Science

Background:

• Soft microfluidic channels, modeling vascular capillaries, are formed by cylindrical cavities in soft solids.
• Pressurized fluid flow in these channels can induce instabilities.
• Understanding these instabilities is crucial for channel stability and novel applications.

Purpose of the Study:

• To experimentally and theoretically characterize the peristaltic elastic instability in soft microfluidic channels.
• To determine the critical conditions and wavelength of the instability.
• To explore the potential of this instability for fabricating microstructures.

Main Methods:

• Experimental observation of channel dilation and instability under pressurized fluid flow.
• Theoretical modeling using incompressible neo-Hookean solid mechanics.
• Numerical simulations to fully characterize the instability and its parameters.
• Investigation of material properties, including Gent strain-stiffening.

Main Results:

• Homogeneous dilation precedes a supercritical peristaltic elastic instability.
• Instability occurs at a cavity pressure exceeding 2.052μ, with a characteristic wavelength of 12.278a.
• In finite solids, instability modes shift to long-wavelength bulging in thin-walled cylinders.
• Peristalsis is sustained in Gent materials with significant extensibility.

Conclusions:

• The peristaltic elastic instability is a key failure mode for pressurized soft channels.
• This instability can be controllably utilized to create periodically undulating channels.
• Such engineered channels have potential applications as waveguides with tunable photonic or phononic stop bands.