ABSTRACT
Modeling of estuarine hydrodynamics is often carried out in an Eulerian reference frame. The transport processes which take place in tidal estuaries are convection dominated and can be better represented by Lagrangian treatments. This chapter draws particular attention to the contrasting Eulerian and Lagrangian modeling approaches. What is the difference between the Eulerian point of view and the Lagrangian point of view? Simply stated, an Eulerian approach treats all dependent variables as functions of fixed coordinates and time, while a Lagrangian treatment considers the dependent variables as functions of time and their initial positions. The contrasting Eulerian and Lagrangian practices are used in field observations as well. Any in situ measurements of current, temperature, salinity, water quality parameter, etc. are typical examples of Eulerian measurements. It has been recognized that the movements of water mass in tidal estuaries are more inclined to be Lagrangian than Eulerian in nature.
