Before revision:  We go on to use the general method to derive a novel, mathematical robust, finite difference method for solving the 2D diffusion equation within a 1D reduced-dimension model  .
After revision:  We go on to use the general method to derive a novel, mathematical robust, finite difference method for solving the 2D diffusion equation within a 1D reduced-dimension model . The methods described here can be used to improve the accuracy of many reduced-dimension models while retaining benefits of system simplification .