DYNLET1: Dynamic Implicit Numerical Model of One-Dimensional Tidal Flow Through Inlets
The development and verification of a simple model of inlet hydrodynamics for use in reconnaissance-level quantitative studies of inlets are presented. The model, named DYNLET1 for its one-dimensional modeling of the dynamic (time-independent) behavior of tidal flow at inlets, is based on the full one-dimensional shallow-water equations employing an implicit finite difference technique. The model is intended for personal computer (PC) users having little or no experience in numerical modeling and facilities minimal data entry and numerical grid generation. DYNLET1 can predict flow conditions in channels with varied geometry, and it accepts varying friction factors across an inlet channel, geometric boundary conditions. Values of water surface elevation and average velocity are computed at locations across and along inlet channels and displayed on the PC monitor and written to output files for possible further analysis. The inlet to be modeled bay consist of a single channel connecting the sea to the bay, or it can be a system of interconnected channels, with or without bays. The principal limitation of DYNLET1 is potential inaccuracy in situations where strong two-dimensional flow fields, such as gyres, exist perpendicular to the major axis of channels comprising the modeled inlet. The report also includes a short review of existing, similar simple models of tidal inlet hydrodynamics. Application and verification of the model are illustrated with two case studies for which extensive data are available: Masonboro Inlet, North Carolina, and Indian River Inlet, Delaware.