GGU-3D-SSFLOW: "Velocities + gradients" menu item

The velocity field can be visualised using this menu item. The size and direction of the seepage velocity are shown (vs = (k · i)/neff!).

First, enter the length of the maximum seepage velocity to be displayed. You can then decide whether the velocities or the gradients are to be displayed.

By selecting the "Velocity arrows at nodes" check box, you can determine whether or not the velocities are to be displayed at the nodes or at the centroids of the triangular elements. The velocity at the centroid is determined by the program from the FEM analysis. The velocities at the element nodes are determined as a mean of the centroid velocities of the neighbouring triangular elements. The length of the maximum velocity vector must be given in the user-defined length unit (generally metres). Scale information with the unit length/time is shown in the general legend on your output sheet. The colour of the arrowheads can be edited using the "Graphics preferences/Pen colour and width" menu item.

For systems with, e.g., wells, very high velocities occur in the area of the well, which may possibly ruin the graphics. Select a length for which velocities should still be presented and activate the corresponding switch.

Additional visualisation preferences can be specified at the bottom of the dialog box. For example, all arrows may be drawn the same length or a small animation be displayed. The arrows can also be visualised in an array, if necessary corrected by the program to suit the geometry of the triangular elements.

As the program calculates with unsaturated permeabilities, potentials in the unsaturated zone are the result, which is physically absolutely correct. From experience, this confuses some clients. To save long discussions, switch off the potential lines in the unsaturated zone with the corresponding check box.