Flow Boundary Condition Editor

Owned by Kester Scandrett
Last updated: 20 Apr, 2018
2 min read

For flow BC’s the Cell by Cell Options frame has several useful functions.  The Edit button allows the user to edit the associated time series. The All buttons next to the fields in this subframe allow the user to quickly assign all the boundary cells in the current group to the parameter specified in the adjacent field.  For example, pressing the All next to the Flow Table field shown in  Figure 1 would set the flow series number for all cells in the group to the current “NC Q50” table settings. If the user has an input flow series for a river that requires distributing the river flow across several cells, the single time series of flow can be specified in the Flow Table and the Factor can be set to split the flow appropriately among the cells.  The Dist Factors button sets the Factor based on cell volumes.  A constant inflow can also be distributed in a similar manner by using the Dist Flow button next to the Constant Flow field.

The Cell by Cell Options frame also provides the Apply Flow Files button, allowing the user to import flow with the flow files to build a cell by cell variable inflow series.  This feature is predominantly used in wetting and drying models. 

The user interface for boundary conditions has a uniquely designed editor with drop down menus for concentration table assignment to flow tables. When the user selects Flow Table as shown in  Figure 1, they can use drop down menu items to link flow tables with concentration tables. As with earlier versions of EFDC_Explorer, the concentrations specified in the Constant Concentrations frame are only used with constant flows.  Specifying a constant salinity concentration of 5 ppt in the Constant Concentrations frame but with zero constant flow, even if the boundary has flows assigned via a time series, the salinity input to the model will be zero.  If using a time series for flows, the user must use a time series to assign salinities, even if they are constant. Note that the water column concentration settings, for both time series and constant, are fixed for all cells for the same group.

The Momentum Options frame for the flow boundaries provides the user with more control over how EFDC handles momentum flux on the cell faces. The options now include:

  • Inflow Momentum Flux Ignored (default option)
  • Momentum Flux on West U Face
  • Momentum Flux on South V Face
  • Momentum Flux on East U Face
  • Momentum Flux on North V Face

The Flow Multiplier Switch subframe provides a drop-down box with a number of options, from normal inflow to various lateral inflow/outflow options. Constant concentrations and time variable Concentration Tables may also be edited from this frame.

Figure 1  Boundary condition settings – Flow boundary.