Long-time rotational motion of a rigid body immersed in a viscous fluid

A rigid body, immersed in a viscous incompressible fluid, and set in motion by a small applied torque of short duration, comes to rest very slowly. The time-dependence may be calculated from the frequency-dependent friction matrix. At long times the rotational velocity decays as t−5/2 with a coefficient which depends on the shape of the body. The rotational velocity autocorrelation function of a Brownian particle has the same time-dependence