Fine-mesh limit of 1D nodal transport equations

Embedded in multidimensional nodal transport codes is the solution of transverse integrated ID transport equations. Since, in this solution, fluxes on boundaries are DP1, it is generally assumed that the ID solutions, in the small-mesh limit, approach DP1 solutions. It will be shown that this is not true. Small-mesh limits of the ID nodal equations will be derived, and it will be shown that these are substantially worse than the DP1 equations under certain circumstances. Alternate ID nodal equations (which do have a DP1 small-mesh limit) are proposed