CMS-Flow/Boundary Conditions

The CMS-Flow Arc Boundary Conditions dialog

All numeric models require boundary condition data. In CMS-Flow, boundary conditions are defined on feature arcs in a boundary conditions coverage.

The Create Feature Arc tool can be used to click out boundary conditions for the model or arcs can be converted from other coverages or modules. Arcs can also be imported.

Once the boundary condition arcs have been created, right-click on the arc with the Select Feature Arc tool and select the Assign Boundary Conditions command to bring up the Arc Boundary Condition dialog.

Arc Boundary Conditions Dialog[edit source]

This dialog has the following options for boundary condition parameters.

• Name — Assign a name to the boundary arc.
• Type — Has the following options:
  • "Unassigned" — The default option.
  • "Flow rate forcing" — Specifies an inflow rate (flow in cubic meters/second at each cell). This can be used to represent a river flowing into the domain.
    • Flow Source — Specifies a time series of water fluxes as either a constant value or as a curve.
      • "Constant" — Allows entering a Constant flow value for the flow rate in m^3/s per cell.
      • "Curve" — Clicking the Curve button will bring up an XY Series Editor dialog where a time series of water fluxes can be entered.
    • Specify inflow direction — Measured clockwise from North (degrees). Positive values are directed into the domain and negative values are leaving the domain. Will be perpendicular to the cell face if no value is set.
    • Conveyance coefficient — Distributes the total volume flux across the boundary to estimate depth-averaged velocities. Default is equal to approximately 2/3 for uniform flow.
  • "WSE forcing" — Specifies the water surface elevation as a function of time for the cellstring. Options include specifying a single curve (water level -vs- time) and all the cells will have the same water level at the specified time and extracting individual curves for each cell either from a regional tidal database (ADCIRC database) or from a regional (larger) circulation model.
    • WSE Source — The following WSE sources can be selected:
      • "Constant" — Allows setting a Constant WSE value for the water surface elevation.
      • "Curve" — Clicking the Curve button will bring up an XY Series Editor dialog where a time series for the water surface elevation can be entered.
      • "Parent CMS-Flow" — This option will extract multiple time series curves from a larger CMS-Flow grid. Clicking the Select button will allow choosing the CMS-Flow data file.
      • "Parent ADCIRC" — This option will extract multiple time series curves from an ADCIRC model. This type provides an option to Use Velocity from the ADCIRC model. The Parent grid (fort.14) file, ADCIRC Solution File Type, Parent solution file, and Parent Starting Time will all need to be selected.
      • "Extracted" (added in SMS 13.4+) — Option to pre-extract boundary forcing from a loaded parent grid or mesh. This type provides an option to Force Velocity from the parent.
        • Note: User must ensure times for water level and velocity, if applicable, are identical.
        • If not, they can use the Sample time steps tool in the Dataset Toolbox.
      • "Harmonic" — Option of forcing with a harmonic water surface elevation. With this option, the type of Speed, the Amplitude and the Phase can be entered in rows on the table.
      • "Tidal Constituent" — Option of forcing with a tidal water surface elevation. With this option, the type of Constituent, the Amplitude and the Phase can be entered in rows on the table. Insert and delete rows to determine the constituents that will be used in the model run.
      • "External Tidal" — This option tells the CMS to expect a "Tidal Constituents" simulation to be added and applied to the CMS-Flow solution. Guidance for this step is given on the page, Tidal Components.
    • WSE offset — An assumed spatially and temporally Constant or temporally varying Curve that may be used to correct the boundary water surface elevation for vertical data and sea level rise.
• Salinity — When this option is turned on, clicking the Curve button will bring up an XY Series Editor dialog where a time series of salinity values can be entered.
• Temperature — When this option is turned on, clicking the Curve button will bring up an XY Series Editor dialog where a time series of temperature values can be entered.