Numerical Analysis of the Thin-Film Flow on a Spinning Doughnut-Shaped Substrate.

Thin-film flow on a spinning doughnut-shaped substrate was analysed numerically. A simple one-dimensional non-Newtonian flow model was employed to calculate the film flow. The time-dependent change in the rheology of the film liquid, due to the evaporation of solvents in the liquid, which is spatially varying, was considered in the calculation. According to the numerical experiments, the spatial distribution of the solvents' evaporation rate, as well as the liquid rheology, showed a significant effect on the final thickness distribution of the film. On the other hand, the initial thickness distribution of the film did not show any effect on the final thickness distribution.