We propose a derivation of a nonequilibrium Langevin dynamics for a large particle
immersed in a background flow field. A single large particle is placed in an ideal gas
heat bath composed of point particles that are distributed consistently with the
background flow field and that interact with the large particle through elastic
collisions. In the limit of small bath atom mass, the large particle dynamics converges in
law to a stochastic dynamics. This derivation follows the ideas of [P. Calderoni, D. Dürr
and S. Kusuoka, J. Stat. Phys. 55 (1989) 649–693. D. Dürr,
S. Goldstein and J. Lebowitz, Z. Wahrscheinlichkeit 62
(1983) 427–448. D. Dürr, S. Goldstein and J.L. Lebowitz. Comm. Math. Phys.
78 (1981) 507–530.] and provides extensions to handle the nonzero
background flow. The derived nonequilibrium Langevin dynamics is similar to the dynamics
in [M. McPhie, P. Daivis, I. Snook, J. Ennis and D. Evans, Phys. A
299 (2001) 412–426]. Some numerical experiments illustrate the use
of the obtained dynamic to simulate homogeneous liquid materials under shear flow.