Synergetic fluid mixing from viscous fingering and alternating injection

Area of Science:

• Fluid dynamics
• Microfluidics
• Chemical engineering

Background:

• Mixing fluids with different viscosities in microfluidic channels is challenging.
• Viscous fingering can occur at interfaces of fluids with differing viscosities.
• High Péclet numbers indicate slow diffusion and fast advection, making mixing difficult.

Purpose of the Study:

• To investigate the combined effect of alternating injection and viscous fingering on mixing efficiency.
• To develop a theoretical model for predicting mixing in such systems.
• To provide a design tool for optimizing microfluidic mixing.

Main Methods:

• High-resolution simulations were used to observe fluid behavior.
• A macroscopic model was developed combining hyperbolic and dissipation models.
• The model was validated against simulation data.

Main Results:

• The synergetic action of alternating injection and viscous fingering significantly increases mixing efficiency.
• A theoretical model was successfully developed to predict mixing evolution.
• The model quantitatively reproduces the average degree of mixing.

Conclusions:

• Alternating injection coupled with viscous fingering is a powerful strategy for enhancing microfluidic mixing.
• The developed macroscopic model serves as a valuable design tool for optimizing mixing processes.
• This approach has potential applications in various microfluidic applications requiring efficient mixing.