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Transición discontinua a turbulencia nemática activa
Malcolm Hillebrand1,2,3, Ricard Alert4,5,6,7,8,9
1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
Nature communications
|December 15, 2025
Resumen
La transición a la turbulencia activa en fluidos activos es discontinua, presentando un salto repentino en la velocidad y bistabilidad entre estados de flujo laminar y caótico. Esto contrasta con las transiciones continuas observadas en sistemas confinados.
Área de la Ciencia:
- Física
- Dinámica de fluidos
- Física de materia blanda
Sus antecedentes:
- Los fluidos activos exhiben flujos caóticos a bajos números de Reynolds, denominados turbulencia activa.
- Las propiedades estadísticas de la turbulencia activa se comprenden, pero la transición de flujo laminar a turbulento sigue sin estar clara.
Objetivo del estudio:
- Investigar la transición de flujo laminar a turbulento en nemáticas activas no acotadas y sin defectos.
- Caracterizar la naturaleza de esta transición, ya sea continua o discontinua.
Principales métodos:
- Simulaciones de un modelo mínimo para nemáticas activas.
- Análisis de la velocidad cuadrática media, bistabilidad, histéresis y exponentes de Lyapunov de tiempo finito.
Principales resultados:
- La transición a la turbulencia activa es discontinua, marcada por un salto en la velocidad cuadrática media.
- Se observó bistabilidad e histéresis entre flujos laminares y caóticos.
- Se identificó un número de actividad crítico (A* ≈ 4900) para la transición.
- Se producen bifurcaciones subcríticas que conducen a oscilaciones y transitorios caóticos largos por debajo de la transición.
Conclusiones:
- La transición a la turbulencia activa en nemáticas activas no acotadas es discontinua.
- Es probable que las interacciones hidrodinámicas de largo alcance en el flujo de Stokes supriman la coexistencia espacial de los estados de flujo, lo que conduce a la transición discontinua.
- Los hallazgos contrastan con las transiciones continuas en sistemas confinados.
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