We present a simple and accurate method of estimating the translational hydrodynamic friction on rigid Brownian particles of arbitrary shape. The Brownian friction coefficient f takes the form f=6πη${\mathit{C}}_{\mathrm{\Omega }}$, where ${\mathit{C}}_{\mathrm{\Omega }}$ is mathematically equivalent to the electrostatic capacitance of the particle Ω in units where the capacity of a sphere equals its radius. This formula is particularly useful for particles consisting of a few globular subunits, for which slender body approximations are not very accurate.

• Received 8 January 1993

DOI:https://doi.org/10.1103/PhysRevE.47.R2983