Fluctuations in fluids in thermal nonequilibrium states below the convective Rayleigh-Benard instability

Citation
Jmo. De Zarate et Jv. Sengers, Fluctuations in fluids in thermal nonequilibrium states below the convective Rayleigh-Benard instability, PHYSICA A, 300(1-2), 2001, pp. 25-52
Citations number
59
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICA A
ISSN journal
0378-4371 → ACNP
Volume
300
Issue
1-2
Year of publication
2001
Pages
25 - 52
Database
ISI
SICI code
0378-4371(20011101)300:1-2<25:FIFITN>2.0.ZU;2-4
Abstract
Starting from the linearized fluctuating Boussinesq equations we derive an expression for the structure factor of fluids in stationary convection-free thermal nonequilibrium. states, taking into account both gravity and finit e-size effects. It is demonstrated how the combined effects of gravity and finite size cause the structure factor to go through a maximum value as a f unction of the wave number q. The appearance of this maximum is associated with a crossover from a q(-4) dependence for larger q to a q(2) dependence for very small q. The relevance of this theoretical result for the interpre tation of light scattering and shadowgraph experiments is elucidated. The r elationship with studies on various aspects of the problem by other investi gators is discussed. The paper thus provides a unified treatment for dealin g with fluctuations in fluid layers subjected to a stationary temperature g radient regardless of the sign of the Rayleigh number R, provided that R is smaller than the critical value R-c associated with the appearance of Rayl eigh-Benard convection. (C) 2001 Elsevier Science B.V. All rights reserved.