General Module Function
The capture_zone module utilizes streamlines technology to determine the volumetric regions of your model for which groundwater flow will be captured by one or more extraction wells.
Module Input Ports
capture_zone has three input ports. The selected nodal data component to the left input port must be a vector representing seepage velocity. The middle input port receives the nodal coordinates of the well(s) and does not require any data associated with the wells as only the coordinates are used. The right input port receives the z-scale (exaggeration) associated with BOTH input ports.
Module Output Ports
capture_zone has only one output port. The port outputs the original mesh with three new nodal data components.
Module Control Panel
The control panel for capture_zone is shown in the figure above. Many of the parameters are related to streamline interpolation which is discussed in the streamlines help.
The Seepage Velocity radio buttons display all data components (vector and scalar) passed to capture_zone. By default, the first (0th) component is selected.
The Zscale type-in reflects the value of the z exaggeration port.
The Well Capture Distance type-in is used to specify the maximum distance that a streamline must pass near an extraction well before that streamline's integration is terminated and it's original starting location is deemed to have been captured by a well. Setting this value too high may result in regions that are designated as being captured but are not. However, setting it too low may also result in incorrect determination of which (if any) well is responsible for capturing regions. Fortunately, the acceptable bounds for this parameter are rather wide and generally a value corresponding to one nominal cell width (those cells in the region of your wells) is appropriate.
The Minimum Flow Velocity type-in is used to specify the minimum velocity that will be considered in the integration. If the magnitude of the velocity field in a region is less than this minimum value, streamlines will end in that region (or will not be produced if the velocity at a starting point is less than the minimum). Setting this to a lower value will more accurately define the FULL extent of the capture zone region. However lower values may increase run time. The default value is 0.000001.
The Segments per Cell slider is used to set the number of integration steps to be used in each cell (i.e., the number of divisions of the cells) to calculate the streamline. The default is one and the range is 1 to 16.
The Order slider is used to set the order of the integration. Higher order integration is more accurate, but executes much slower. The default is one and the range is 1 to 4.
The Max Segments Total slider is used to set the maximum allowable number of streamline segments that will be completed for each streamline. If the number of segments along a streamline exceeds the max number, the streamline is terminated at the end of the last (max) segment. The default is 15 and the range is 1 to 1000.
The Extinction Angle slider is used to specify the maximum allowable angle between successive line segments before integration (streamline generation) should be terminated. The default value is 130 degrees.