Tagged particle fluctuations in uniform shear flow

M. Cristina Marchetti, James W. Dufty

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The nonlinear Boltzmann and Boltzmann-Lorentz equations are used to describe the dynamics of a tagged particle in a nonequilibrium gas. For the special case of Maxwell molecules with uniform shear flow, an exact set of equations for the average position and velocity, and their fluctuations, is obtained. The results apply for arbitrary magnitude of the shear rate and include the effects of viscous heating. A generalization of Onsager's assumption of the regression of fluctuations is found to apply for the relationship between the equations for the average dynamics and those for the time correlation functions. The connection between fluctuations and dissipation is described by the equations for the equal-time correlation function. The source term in these equations indicates that the "noise" in this nonequilibrium state is qualitatively different from that in equilibrium, or even local equilibrium. These equations are solved to determine the velocity autocorrelation function as a function of the shear rate.

Original languageEnglish (US)
Pages (from-to)255-277
Number of pages23
JournalJournal of Statistical Physics
Issue number2
StatePublished - Aug 1983
Externally publishedYes


  • Boltzmann equation
  • Nonequilibrium fluctuations
  • kinetic theory
  • shear flow
  • velocity autocorrelation function

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics


Dive into the research topics of 'Tagged particle fluctuations in uniform shear flow'. Together they form a unique fingerprint.

Cite this