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Area of Science:

  • Physics
  • Soft Matter Physics
  • Fluid Dynamics

Background:

  • Active nematic fluids are complex systems exhibiting spontaneous motion and orientational order.
  • Understanding the stability and phase behavior of these fluids is crucial for various applications.

Purpose of the Study:

  • To investigate the stability of homogeneous active nematic states.
  • To identify universal mechanisms driving phase separation in active fluids.

Main Methods:

  • Development of a phenomenological continuum theory for active nematic fluids.
  • Application of numerical and analytical tools to study system behavior near critical points.

Main Results:

  • Identification of a universal, model-independent instability in active nematic fluids.
  • Demonstration that this instability drives phase separation into ordered, banded structures.
  • Observation that nematic order is perpendicular to the density gradient in separated phases.

Conclusions:

  • The homogeneous nematic state is inherently unstable to order fluctuations.
  • Phase separation into banded structures is a universal feature of active fluids, independent of specific symmetries.
  • The findings provide fundamental insights into the self-organization of active matter.