Taming Taylor-Aris dispersion through chaotic advection

Area of Science:

• Analytical Chemistry
• Fluid Dynamics
• Separation Science

Background:

• Taylor-Aris dispersion increases the Height Equivalent of the Theoretical Plate (HETP) in pressure-driven liquid chromatography, limiting high-throughput operations.
• Previous research mitigated dispersion in microchannels using helical flow streamlines.
• Further reduction of axial dispersion is explored through chaotic flow conditions.

Purpose of the Study:

• To investigate the reduction of axial dispersion in microfluidic systems by generating chaotic streamlines.
• To analyze the impact of regular, partially chaotic, and globally chaotic flow regimes on solute dispersion.
• To validate theoretical predictions with particle ensemble simulations.

Main Methods:

• A three-dimensional steady flow was created by combining pressure-driven Poiseuille flow with electroosmotic flow.
• Brenner's macrotransport approach was employed to predict the axial dispersion coefficient.
• Lagrangian-stochastic simulations of particle ensembles were used for validation.

Main Results:

• Taylor-Aris dispersion can be suppressed in globally chaotic flow regimes.
• Brenner's macrotransport theory accurately predicts dispersion coefficients for various chaotic flow features.
• Lagrangian-stochastic simulations confirmed the theoretical predictions.

Conclusions:

• Globally chaotic kinematics offer a pathway to eliminate Taylor-Aris dispersion in microfluidic chromatography.
• The combination of macrotransport theory and spectral analysis provides a theoretical framework for understanding mixing in chaotic flows.
• This approach has significant implications for enhancing separation efficiency and throughput in chromatography.