Modeling support for dynamic simulation of chemical-process flowsheets, which is of significant value for plantwide dynamic simulation using differential–algebraic model formulations, is to date very limited when one or more unit models include partial differential equations. Several new techniques that provide modeling support for such simulations are presented. These techniques are based on a generalized characteristic analysis and a differentiation index analysis of partial differential–algebraic models. They can be used to uncover systems that cannot be solved as part of a dynamic simulation, and to determine whether or not the initial and boundary conditions supplied by the modeler form a well-posed problem. In a network flow context, they can further be used to select, enforce, and adapt the boundary conditions as required to maintain automatically a mathematically well-posed problem. Each of these provides time-saving support to the system modeler.