Interface Dynamics of Wet Active Systems

Area of Science:

• Soft Matter Physics
• Active Matter Systems
• Interface Dynamics

Background:

• Phase-separated active suspensions exhibit complex interfacial behavior.
• Understanding interface roughening is crucial for predicting material properties and dynamics.
• Existing models often simplify fluid interactions and substrate effects.

Purpose of the Study:

• To characterize the universality class of interface roughening in active suspensions on substrates.
• To investigate the influence of fluid flow and substrate friction on interfacial dynamics.
• To determine the length scales governing interface randomization.

Main Methods:

• Analysis of interfacial dynamics in phase-separated active suspensions.
• Comparison of experimental or simulation data with theoretical models, specifically the |q|KPZ universality class.
• Examination of early-time dynamics and the impact of system size.
• Investigation of the role of substrate friction and interfacial tension.

Main Results:

• Interfacial dynamics at large length and time scales belong to the |q|KPZ universality class, irrespective of long-ranged fluid flows.
• At early times or in small systems, roughening exponents resemble those in momentum-conserving fluids.
• A de Gennes-Taupin length scale, dependent on interfacial tension, governs interface randomization when substrate friction is negligible.

Conclusions:

• The |q|KPZ universality class accurately describes interface roughening in active suspensions under specific conditions.
• Fluid flow does not alter the large-scale universality class, highlighting robust scaling behavior.
• Substrate friction and interfacial tension play critical roles in determining the randomization length scale of interfaces.