A flow line represents a path of fluid flow through the material. Flow occurs in the direction of decreasing Total Head. For a material with isotropic permeability, flow lines are perpendicular to contours of Total Head.
Flow lines can be added individually to a model, with the Add Flow Line option, or multiple flow lines can be simultaneously generated with the Add Multiple Flow-Lines option.
To add individual flow lines with the Add Flow Line option:
Select Add Flow-Line from the toolbar or the Lines sub-menu in the Groundwater menu.
You will be prompted to enter a starting location for a flow line. You can do this graphically with the mouse, or enter an x,y coordinate pair in the prompt line.
Enter the starting point, and the flow line will be generated. An arrow symbol on the flow line will indicate the direction of flow.
NOTE: from the starting point you have entered, the flow line is only generated in the direction of flow (i.e. in the direction of decreasing Total Head). Therefore, in general, you will probably want to enter a starting location which is at a high Total Head value (i.e. usually at one edge of the external boundary). You may therefore want to view Total Head contours while you are adding flow lines, although you can add flow lines while viewing any contoured data.
You can add as many flow lines as you wish, by repeating Step 3.
When you are finished adding flow lines, press Escape, or right click and select Cancel, to exit the Add Flow Line option.