Lateral boundary conditions allow one to constrain the physics along boundaries in the model. They are similar to initial conditions, which specify the model state at start time. As an example, at the walls of a bathtub, the flow normal to the walls is zero since they are impermeable. For general information on the topic, see the Wikipedia article. Since ADCIRC solves for water elevations and velocities (fluxes), typically one (occasionally both) of these two quantities are constrained at the lateral boundaries.
By default ADCIRC weakly satisfies the no-flux boundary condition at mesh boundaries. See flux specified boundaries for details on fine-grained specification of the flux boundary conditions if required.
Automatic Specific of Boundary Conditions
The OceanMesh2D(GitHub site) mesh generation toolbox has the ability to automatically apply the basic no-flux and open ocean elevation boundary conditions for an ADCIRC mesh. See the makens (make node-string) function using the 'auto' option. Geospatial shoreline data is required to automatically detect whether a mesh boundary is located in the ocean (applies open ocean elevation boundary condition) or is along the shoreline/on-land (applies natural no-flux boundary condition).
The makens function also contains other options for manually specifying other boundary condition types such as rivers and weirs.
- Roberts, K. J., Pringle, W. J., & Westerink, J. J. (2019). OceanMesh2D 1.0: MATLAB-based software for two-dimensional unstructured mesh generation in coastal ocean modeling. Geoscientific Model Development, 12, 1847–1868. https://doi.org/10.5194/gmd-12-1847-2019