DHIJWASv Software FEFLOW 6.1

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Dealing with spatial data requires the definition of a
unique coordinate system as a reference. FEFLOW can
use data in any metric cartesian system, i.e., any system
with orthogonal x and y axes and coordinates in meters.
The most popular of these systems is the UTM coordinate
system.
To achieve better precision in the calculations,
FEFLOW always uses a local and a global coordinate
system at the same time. The axes in both systems have
the same orientation, only the origin of the local system
has an offset in global coordinates.
Locations in the local system can be expressed in
cartesian or polar coordinates. The coordinate system
used in a particular view window can be defined in the
View menu. The offset of global and local coordinate
system is defined automatically via map extents or
manually when starting a new model, but can be edited
later on in the Coordinate-System Origin dialog which
is accessed with a click on the Edit Origin button in the
Origin toolbar. In practical cases, it is usually sufficient
to deal with the global coordinate system.
In 2D cross-sectional and axisymmetric models the
y coordinate refers to the elevation. In these cases an
offset between local and global coordinates in y should
be avoided so that there is no doubt about the elevation
reference. Internally, FEFLOW uses the local y coordinate
as the reference for elevation-dependent parameters,
e.g., when converting hydraulic head to pressure
head and vice versa.
Figure 4.2 Global and local coordinates (2D/3D).