Forces exerted by a correlated fluid on embedded inclusions

Abstract

We investigate the forces exerted on embedded inclusions by a fluid medium with long-range correlations, described by an effective scalar field theory. Such forces are the basis for the medium-mediated Casimir-like force. To study these forces beyond thermal average, it is necessary to define them in each microstate of the medium. Two different definitions of these forces are currently used in the literature. We study the assumptions underlying them. We show that only the definition that uses the stress tensor of the medium gives the sought-after force exerted by the medium on an embedded inclusion. If a second inclusion is embedded in the medium, the thermal average of this force gives the usual Casimir-like force between the two inclusions. The other definition can be used in the different physical case of an object that interacts with the medium without being embedded in it. We show in a simple example that the two definitions yield different results for the variance of the Casimir-like force.

15 pages, 2 figures

References in corpus (17)

• The `Friction' of Vacuum, and other Fluctuation-Induced Forces
• The Casimir effect: from quantum to critical fluctuations
• Stresses in lipid membranes
• Drag forces in classical fields
• Critical dynamics in thin films
• Fluctuations of Fluctuation-Induced "Casimir" Forces
• Critical Casimir interaction of ellipsoidal colloids with a planar wall
• Relaxation phenomena at criticality
• Forces Induced by Non-Equilibrium Fluctuations: The Soret-Casimir Effect
• The out of equilibrium behavior of Casimir type fluctuation induced forces for free classical fields
• Fluctuations of the Casimir-like force between two membrane inclusions
• Drag forces on inclusions in classical fields with dissipative dynamics
• Violation of action--reaction and self-forces induced by nonequilibrium fluctuations
• Generalized Casimir forces in non-equilibrium systems
• Effective interactions between inclusions in complex fluids driven out of equilibrium
• Membrane stress tensor in the presence of lipid density and composition inhomogeneities
• Dynamical approach to the Casimir effect

Cited by in corpus (11)

• Stresses in non-equilibrium fluids: Exact formulation and coarse grained theory
• Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques
• Thermal Casimir drag in fluctuating classical fields
• Diffusion of a particle quadratically coupled to a thermally fluctuating field
• Out of equilibrium thermal Casimir effect in a model polarizable material
• Attraction/repulsion switching of non-equilibrium depletion interaction caused by blockade effect in gas of interacting particles. II
• Induced long-time correlations in a two-component lattice gas
• On The Critical Casimir Interaction Between Anisotropic Inclusions On A Membrane
• Viscosity of a sheared correlated (near-critical) model fluid in confinement
• Membrane-mediated interactions
• On the dynamics of the interaction between triggered active inclusions