Streamfunction and Complex Potential - Environmental Modeling - page 288

With the final command new mesh-spacing vectors are computed. With the latter
the arrow plot is performed. For fine meshes the arrows become unidentifiable, and
thus it is better to visualize them on a coarser grid.
In the last command block a figure is composed out of filled contours, contours
and arrows. This has to be done separately for a well gallery on one side and
a vortices system on the other side. For the well option, the real part of the complex
potential represents the real potential and the contours are given in blue color. The
streamline command is started twice, once forward and once backward. This is
realized by changing the sign in the velocity component. The user may increase the
performance of the execution by choosing the correct set of start values for each
streamline command. In the final if block the arow field is plotted. The course
mesh is computed first and stored in variable z . Then the velocity field is re-
calculated, based on another evaluation of the complex potential, before the
quiver command plots arrows in the figure.
i
For the vortex option the same tasks are performed but with slightly different
details. The filled contour plot gets white isolines, as these represent streamlines in
this case. The lines, plotted with the streamline command, are is-potentials in the
vortex case and are thus plotted in blue. For the arrow field, it has to be taken into
account that the real part of the complex potential represents the streamfunction,
and thus the velocity components have to be computed following the ( 15.1 ).