incorporates post-processing facilities within the
Visualization Tab which permit detailed inspection of volume meshes.
Through the use of "crinkle cuts", isolated portions of the volume mesh may be
examined to ensure such satisfies all modeling requirements.
A crinkle cut is a faceted surface composed of those uncut faces of all tetrahedral
elements intersected by a prescribed cutting plane, and it provides insight as to the
nature of the mesh local to the cutting plane.
A description of the controls provided for the generation of crinkle cuts is provided
Cutting Plane Specification
Crinkle cuts are generated from the volume mesh based upon the placement of a
cutting plane, and controls for this specification are provided in the Cutting Plane
panel shown below.
The facilities included permit the user to orient the cutting plane in a
variety of ways. The series of radio buttons permits
rapid specification of cutting planes
which are perpendicular to the coordinate axes, or for more general
positioning, the Other radio button may be activated.
This option will require user input of vector components in the text
fields immediately below in order to define the normal vector for
the desired cutting plane.
The absolute direction of the vector is unimportant,
and components need not define a unit vector; such are
accepted and transparently normalized once the Set button is pressed.
In this way, cutting planes (and hence crinkle cuts) may be precisely oriented to illuminate specific features of the volume mesh.
Once the desired orientation has been defined, the New button should be pressed to instruct GridEx to generate
the corresponding crinkle cut. This new crinkle cut then becomes
the active crinkle cut which is rendered in red while all others
are rendered in yellow.
A crinkle cut is a selectable
object just as is any other surface, and the rendering properties may be changed as desired.
The Delete button removes only the active crinkle cut from the display.
The Crinkle Cut
Once a crinkle cut has been introduced, it may be readily repositioned within the domain via
translation along its prescribed normal direction.
This is performed using the slider bar in the Cut Position panel shown below.
An upward movement of the central slider control translates the cut plane
along the direction of the prescribed normal while
a downward movement causes a translation counter to the normal direction.
The upper- and lower-most sliders set the respective bounds of the central slider and
may be adjusted to limit the traversal of such.
For cutting planes oriented perpendicular to either of the coordinate axes, the center text field displays the physical position of the cutting plane along the respective axis while the upper and lower fields display the respective bounds within which the plane must be positioned to remain visible.
For arbitrarily oriented cutting planes, the upper and lower fields display the extrema of
the permitted displacements within a bounding box which encloses the entire domain.
When the cutting plane is translated, it is by default rendered as a semi-transparent plane to facilitate visual positioning. Once the slider is released, the corresponding crinkle cut is generated and displayed. The Dynamic toggle button causes the generation of the crinkle cut to be performed dynamically as the slider is adjusted, thus the transparent cut plane is then no longer displayed.
By default, the crinkle cut is composed of the uncut tetrahedral faces
which fall on the side of the cut plane counter to the direction of the prescribed normal. The Toggle button simply reverses this convention; the same tetrahedrons are
cut though an alternate set of faces (which now lie on
the opposite side of the cutting plane corresponding to the positive direction of the normal) are displayed.
Lastly, the reset button simple "centers" the cutting plane given the upper and lower bounds.
Crinkle Cut Statistics
As each crinkle cut is a result of an ordered search within the volume mesh, there are certain
informational details available from this process.
The Cut Statistics panel displays the number of unique
nodes, the number of tetrahedral elements which have been cut, and a unique identifier for the active crinkle cut. Any number of crinkle cuts may be generated and displayed though it is the statistics for the active crinkle cut which are displayed within this panel.
Selection of another crinkle cut makes it the active crinkle cut and also updates the
fields in this panel.