The long-time tail of the angular-velocity autocorrelation function for a rigid Brownian particle of arbitrary centrally symmetric shape

The long-time t−5/2 behaviour of the angular-velocity autocorrelation function is determined by the diffusion of fluid motion to large distances, from where the particle appears a point singularity. From an examination of this flow, the coefficient of t−5/2 can be related to some effective aspect ratios which describe how the particle rotates in a simple shear flow.