We investigate the average time for the earliest particle to hit a spherical absorber when a homogeneous gas of freely diffusing particles with density ρ and diffusivity D is prepared in a deterministic state and is initially separated by a minimum distance l from this absorber. In the high-density limit, this first absorption time scales as l2/D 1/lnρl in one dimension; a similar scaling behavior occurs in greater than one dimension. In one dimension, we also determine the probability that the kth-closest particle is the first one to hit the absorber. At large k, this probability decays as k1/3exp(-Ak2/3), with A = 1.932 99... analytically calculable. As a corollary, the characteristic hitting time Tk for the kth-closest particle scales as k4/3; this corresponds to superdiffusive but still subballistic motion.
|Journal of Statistical Mechanics: Theory and Experiment
|Published - 1 Jun 2014
- large deviations in non-equilibrium systems
- transport processes/heat transfer (theory)