An unstructured mesh generation algorithm for shallow water modeling

The successful implementation of a finite element model for computing shallow water flow requires: (1) continuity and momentum equations to describe the physics of the flow, (2) boundary conditions, (3) a discrete surface water region, and (4) an algebraic form of the shallow water equations and boundary conditions. Although steps (1), (2), and (4) may be documented and can be duplicated by multiple scientific investigators, the actual spatial discretization of the domain, i.e. unstructured mesh generation, is not a reproducible process at present. This inability to automatically produce variably-graded meshes that are reliable and efficient hinders fast application of the finite element method to surface water regions. In this paper we present a reproducible approach for generating unstructured, triangular meshes, which combines a hierarchical technique with a localized truncation error analysis as a means to incorporate flow variables and their derivatives. The result is a process that lays the groundwork for the automatic production of finite element meshes that can be used to model shallow water flow accurately and efficiently. The methodology described herein can also be transferred to other modeling applications.