Exploring Anomalous Fluid Behavior at the Nanoscale: Direct Visualization and Quantification via Nanofluidic Devices

Area of Science:

• Nanofluidics: Study of fluid behavior under nanoscale confinement (2-1000 nm).
• Fluid Mechanics and Thermodynamics: Investigating deviations from classical equations at the nanoscale.

Background:

• Classical fluid assumptions fail at the nanoscale due to dominant surface interactions.
• Surface forces (hydration, van der Waals, electrostatic) significantly influence fluid behavior.
• Anomalous phenomena include ultrafast flow, enhanced ion transport, and altered phase transitions.

Purpose of the Study:

• To investigate nanoscale fluid behaviors using novel nanofluidic tools.
• To examine the applicability of classical equations (e.g., Navier-Stokes, Kelvin) at the nanoscale.
• To identify sources of deviation and explore emergent physics in confined fluids.

Main Methods:

• Development and application of novel nanofluidic devices for precise measurements.
• Experimental quantification of liquid transport, vaporization, and condensation phenomena.
• Comparison of experimental results with classical theoretical predictions and simulations.

Main Results:

• Identified additional resistance in hydrophilic nanochannels due to hydration layers.
• Observed reduced flow resistance in hydrophobic nanochannels due to water slippage.
• Measured evaporation flux exceeding classical predictions in hydrophilic systems; quantified confinement-dependent evaporation coefficients.
• Condensation dynamics deviated from bulk behavior, influenced by confinement scale and mixture composition.

Conclusions:

• Classical fluid mechanics and thermodynamic equations require modification for nanoscale applications.
• Nanofluidic studies deepen fundamental understanding of nanoscale fluid phenomena.
• Findings have significant implications for industrial applications like water desalination, oil recovery, and thermal management.