EM 1110-2-1100 (Part II)
30 Apr 02
Figure II-5-31. First, second, and third normal modes of oscillation for Lake
Ontario (Rao and Schwab 1976)
II-5-7. Numerical Modeling of Long-Wave Hydrodynamics
a. Long wave modeling. Most natural flow systems are extremely complex. They have variable
bathymetry and irregular shorelines and are driven by a combination of tidal, wind, and pressure forcing, as
well as temperature- and salinity-driven density gradient forcing. If a realistic approximation of flow
hydrodynamics is necessary for the formulation of design criteria or testing of design alternatives (for
example), numerical long-wave hydrodynamic models should be used. Although these models are generally
not easy to apply and require mainframe computers, they provide the most accurate flow field approximation.
b. Physical models. Prior to describing example applications of numerical models, physical models
may provide a viable alternative to numerical approaches if the problem of concern is not wind-dominated.
For example, if a physical model of a particular estuary exists, and the problem of interest is of tidal origin,
Water Levels and Long Waves