The NEUF-DIX space project - Non-EquilibriUm Fluctuations during DIffusion in compleX liquids

Area of Science:

• Soft Matter Physics
• Non-equilibrium Thermodynamics
• Fluid Dynamics

Background:

• Diffusion and thermal diffusion create large non-equilibrium fluctuations in liquid mixtures, exceeding equilibrium fluctuations.
• Gravity limits the amplitude of these fluctuations at small wave vectors; microgravity allows full development.
• Linearized hydrodynamics models describe fluctuations under small gradients and stationary conditions.

Purpose of the Study:

• Investigate Non-EquilibriUm Fluctuations during DIffusion in compleX liquids (NEUF-DIX) in microgravity.
• Explore Casimir-like forces induced by non-equilibrium fluctuations.
• Understand fluctuations in multi-component mixtures, colloidal suspensions, and during transient diffusion.

Main Methods:

• Microgravity experiments to study non-equilibrium fluctuations in complex liquids.
• Investigation of transport coefficients and behavior near glass transitions.
• Multi-scale simulations to complement experimental findings.

Main Results:

• Non-equilibrium fluctuations exhibit scale-free power law behavior (q^-4) in microgravity.
• Fluctuations span all length scales parallel to the applied gradient in microgravity.
• Theoretical models adequately describe fluctuation statics and dynamics under specific conditions.

Conclusions:

• Microgravity is crucial for fully observing and understanding large-scale non-equilibrium fluctuations.
• Further research is needed to address complex phenomena like Casimir forces and fluctuations in concentrated systems.
• Combining experiments with simulations offers a comprehensive approach to studying these phenomena.