  Based on the thermodynamic variation, we rigorously derive the
sharp-interface model for solid-state dewetting on a flat substrate in the form
of cylindrical symmetry. The governing equations for the model belong to
fourth-order geometric curve evolution partial differential equations, with
proper boundary conditions such that the total volume of the system is
conserved and the total energy is dissipative during the time evolution. We
propose a variational formulation for the sharp-interface model and then apply
the parametric finite element method for solving it efficiently. Extensive
numerical simulation results are presented lastly to demonstrate the
morphological characteristics for solid-state dewetting.
