Interfacing hydrodynamic and water quality models with the Eulerian-Lagrangian method

Abstract

The problem of interfacing hydrodynamic and water quality models is investigated with emphasis on modeling efficiency, accuracy and flexibility. An Eulerian-Lagrangian type of transport model is proposed for interfacing due to its superior simulation effi­ciency and numerical resolution in advection dominant flows. Comparisons are made between Eulerian models and Eulerian-Lagrangian models through both theoretical analyses and numerical studies of mass conservation and concentration accuracy. A mass conservative model, such as an Eulerian type model, will not necessarily guar­antee concentration accuracy. As part of this research, a three dimensional Eulerian­Lagrangian transport model (ELM3D) is developed and validated. The interfacing efficiency of ELM3D is demonstrated through a series of numerical tracer studies simulating the future outfall in Massachusetts Bay. Comparison against a tradi­tional Eulerian model, ECOMsi, shows that an Eulerian-Lagrangian interfacing with a proper mass correction technique, such as total mass scaling, can serve as an efficient transport tool, which is more robust than conventional Eulerian Models in dealing with advection dominant flows.