title: Physical origin of nonequilibrium fluctuation-induced forces in fluids.
abstract: Long-range thermal fluctuations appear in fluids in nonequilibrium states leading to fluctuation-induced Casimir-like forces. Two distinct mechanisms have been identified for the origin of the long-range nonequilibrium fluctuations in fluids subjected to a temperature or concentration gradient. One is a coupling between the heat or mass-diffusion mode with a viscous mode in fluids subjected to a temperature or concentration gradient. Another one is the spatial inhomogeneity of thermal noise in the presence of a gradient. We show that in fluids fluctuation-induced forces arising from mode coupling are several orders of magnitude larger than those from inhomogeneous noise.
authors: Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA.|Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
authors: T R
authors: TR
authors: Kirkpatrick
authors: Departamento de Física Aplicada I, Facultad de Física, Universidad Complutense, 28040 Madrid, Spain.
authors: J M
authors: JM
authors: Ortiz de Zárate
authors: Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA.
authors: J V
authors: JV
authors: Sengers