There are four similar SUTRA boundary condition panes on the Sutra Features tab of the Object Properties dialog box:
•Specified Head or Specified Pressure,
•Specified Concentration or Specified Pressure,
•Fluid Flux, and
•Mass Flux or Energy Flux.
The SUTRA boundary condition panes are only visible if Evaluated at is set to Nodes.
The Schedule (BCSSCH) combobox is used to select a time schedule and a table where the boundary condition values are defined. The user can select Custom as the time schedule. With a Custom time schedule, the user can specify any time in the boundary condition table. Otherwise, only times defined in the time schedule can be selected.
The boundary condition table has either three or four columns depending on the type of boundary condition to be defined. The first column is always used to specify a Time. This is a time at which the boundary condition changes. The second column (Used) is used to define a formula that will determine whether boundary condition on or off. Different formulas can be used at different times to control the nodes to which the boundary condition applies. The remaining columns vary depending on what type of boundary condition is being defined. However, they always contain formulas defining the boundary condition. For example with a specified pressure boundary condition, the user would define formulas for the specified pressure and the associated concentration. Above the table is an edit box that can be used to specify several formulas at once, To use it select two or more cells in the table where formulas are defined and then enter a formula in the edit box. The formula will be copied to the selected cells.
The user is not required to specify a change in the boundary condition for every time step in the schedule. Only times at which there is a change need to be included in the table.
If the user wishes to program the subroutine BCTIME in SUTRA, the Use BCTime checkbox can be used to specify which nodes have their values set via BCTIME.
For SUTRA 3.0 models in which lakes are used, If Lake water present of absent can be used to override the values selected on the Lake-Boundary Interaction pane of the SUTRA Options dialog box. If Use defaults is selected, the value from the Lake-Boundary Interaction pane will be used.
