Anomalous diffusion in viscoelastic media with active force dipoles

Abstract

With the use of the "two-fluid model", we discuss anomalous diffusion induced by active force dipoles in viscoelastic media. Active force dipoles, such as proteins and bacteria, generate non-thermal fluctuating flows that lead to a substantial increment of the diffusion. Using the partial Green's function of the two-fluid model, we first obtain passive (thermal) two-point correlation functions such as the displacement cross-correlation function between the two point particles separated by a finite distance. We then calculate active (non-thermal) one-point and two-point correlation functions due to active force dipoles. The time correlation of a force dipole is assumed to decay exponentially with a characteristic time scale. We show that the active component of the displacement cross-correlation function exhibits various crossovers from super-diffusive to sub-diffusive behaviors depending on the characteristic time scales and the particle separation. Our theoretical results are intimately related to the microrheology technique to detect fluctuations in non-equilibrium environment.

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Cited by in corpus (9)

• Non-reciprocal response of a two-dimensional fluid with odd viscosity
• Hydrodynamic lift of a two-dimensional liquid domain with odd viscosity
• Mechanochemical enzymes and protein machines as hydrodynamic force dipoles: The active dimer model
• Lateral diffusion induced by active proteins in a biomembrane
• Generalized Three-Sphere Microswimmers
• Active gels, heavy tails, and the cytoskeleton
• Influence of thermal fluctuations on active diffusion at large Péclet numbers
• A three-sphere microswimmer in a structured fluid
• Statistical formulation of Onsager-Machlup variational principle