Rapid multiphase flow dynamics mapped by single-shot MRI velocimetry.

Area of Science:

• Physics
• Chemistry
• Biomedical Engineering

Background:

• Conventional magnetic resonance imaging (MRI) methods have limitations in capturing rapidly changing flow dynamics.
• Existing techniques struggle with high acceleration and require extensive time for velocity mapping.

Purpose of the Study:

• To develop and validate a new, fast MRI method for mapping flow fields with high accelerations.
• To visualize the internal dynamics of droplets during mass transfer and surfactant accumulation.

Main Methods:

• A novel MRI pulse sequence with repeated velocity encoding during single-shot imaging.
• Significantly increased maximum acceleration tolerance compared to standard MRI procedures.
• Application to study toluene droplets in a water counterflow during acetone mass transfer.

Main Results:

• The new MRI method successfully mapped flow fields with velocities varying rapidly along streamlines.
• Achieved up to a two-order of magnitude increase in maximum acceleration compared to conventional methods.
• Visualized the impact of acetone concentration on surfactant accumulation at the droplet surface for the first time.

Conclusions:

• The developed fast MRI technique is highly effective for studying complex fluid dynamics, especially under high acceleration.
• This methodology provides unprecedented insights into interfacial phenomena, such as surfactant behavior during mass transfer.
• The reduced measurement time allows for real-time visualization of dynamic processes previously unobservable.