Civil Engineering Reference
In-Depth Information
Block decomposition
Figure 5.96
Meshing by block decomposition and mapping.
(a)
(b)
Figure 5.97
Section of quadrilaterals dragged along an axis: (a) uniform sections; (b) variable sections.
5.8.6 Drag method and extrusion
By the drag method, planar quad mesh is dragged along a straight line normal to or sometimes
making an oblique angle with the planar mesh to produce hex elements as shown in Figure
5.97. In Figure 5.97a, elements of different size can be generated by dragging the section with
a different pitch, and on the other hand, elements of different cross sections can be produced
by dragging the section along non-parallel edges as shown in Figure 5.97b. Extrusion shares
the same idea with the drag method (Vassberg 1999), except that it is more general in the way
it operates; instead of following a straight line drag path, the section is dragged along a curve,
which can be defined analytically or by a list of control points as shown in Figure 5.98.
5.8.7 Meshing by revolution
Sweeping or meshing by revolution is to generate a 3D mesh by rotating a quad mesh about
a rotation axis as shown in Figure 5.99. What we have to do to generate a hex mesh by
rotating a planar quad mesh is to produce a new set of nodes based on those of the quad
Figure 5.98
Extruding a face of 12 quadrilaterals along a curve.
