Nonequilibrium statistical mechanics of heterogeneous systems. III. Brownian motion of a large particle in an inhomogeneous fluid

On the basis of the Liouville equation for the collection of molecules of a system consisting of a large spherical particle and a fluid, a kinetic equation of Fokker–Planck type is derived for the distribution function of the coordinate and momentum of the particle's center of mass. It is assumed that the fluid is in a hydrodynamically nonequilibrium state due to inhomogeneities of the temperature and the velocity field. A diffusion equation is derived from the obtained kinetic equation, and explicit expressions are found for the coefficients of diffusion, thermodiffusion, and barodiffusion of large particles.