Rotation of a closed torus in the slip regime

During the eighties, Williams investigated analytically the role of jump and slip conditions on neutron diffusion and torque and drag on non-spherical single as well as multiple bodies. This work is of fundamental importance in nuclear science and engineering as well as in aerosol sciences. The investigations related to curvilinear geometries, as the analytical techniques are necessarily applicable to such geometries only, but these provided a range of results and insights not available previously. Inspired by this work, we have been exploring a method based on use of Greenʹs function to solve numerically a range of problems relating to condensation on arbitrarily shaped particles and the torque and drag on them in the jump and the slip regimes. In this paper, we review briefly an analytical result of Williams on torque on a closed torus, andfind that the numerical results are in good agreement with this expression.