Provided by:
felt_3.06-9_i386 
NAME
corduroy - element mesh generation description file format
DESCRIPTION
The corduroy(4fe) file format is used by the corduroy(1fe) application
for describing the desired element mesh generation. In general white
space is unimportant in a file, arbitrary numeric expressions may be
used, and case of keywords is unimportant. As per standard convention,
boldface items represent keywords, italicized items represent the
syntax of the grammar, and items in brackets are optional. The file
syntax is shown below.
[ initialization ]
[ generators ]
end
Initialization
The initialization section occurs first in the file if present. It
defines parameters common to all generators and has the following
syntax.
start-node = expression
start-element = expression
constraint = name
material = name
The default start-node and start-element is one. If a constraint is
given then the name will be assigned to the generated nodes.
Similarly, if a material is given then the name will be assigned to the
generated elements.
Generators
The generators section contains specifications for generating the
elements and the associated nodes. The section has the following
syntax.
[ line-generator ]
[ grid-generator ]
[ quadrilateral-grid-generator ]
[ brick-grid-generator ]
[ triangular-mesh-generator ]
Lines
A line-generator specifies the generation of elements along a line in
three dimensions. The generator has the following syntax.
[ start = triple ]
[ end = triple ]
[ number = expression ]
[ rule = linear | log ]
[ element-type = name ]
where a triple has one of the following forms:
( expression , expression , expression )
( expression , expression )
If the z-coordinate of a triple is not specified then the previously
specified z-coordinate is used. The initial default z-coordinate is
zero. The start and end triples define the starting and ending
coordinates of the line respectively. The number of elements along the
line is specified by number. The rule assignment controls whether the
elements are linearly or logarithmically distributed along the line.
The element-type specifies the type of elements to be generated. The
type of the element defined by name must be a linear element.
Grids
A grid-generator specifies the generation of elements within a three-
dimensional grid. The generator has the following syntax.
[ start = triple ]
[ end = triple ]
[ x-number = expression ]
[ y-number = expression ]
[ z-number = expression ]
[ x-rule = linear | log ]
[ y-rule = linear | log ]
[ z-rule = linear | log ]
[ element-type = name ]
The start and end triples define the diagonally opposite corners of the
grid. The x-number, y-number, and z-number assignments specify the
number of elements along the x, y, and z dimensions respectively.
Similarly, the x-rule, y-rule, and z-rule assignments specify whether
the elements are to be generated linearly or logarithmically along the
x, y, and z dimensions respectively. The type of the element specified
by name must be a linear element.
Quadrilateral Grids
A quadrilateral-grid-generator specifies the generation of four-node
planar elements within a two-dimensional grid. The generator has the
following syntax.
[ start = pair ]
[ end = pair ]
[ x-number = expression ]
[ y-number = expression ]
[ x-rule = linear | log ]
[ y-rule = linear | log ]
[ element-type = name ]
The start and end pairs define the diagonally opposite corners of the
grid. The x-number, and y-number assignments specify the number of
elements along the x and y dimensions respectively. Similarly, the x-
rule, and y-rule assignments specify whether the elements are to be
generated linearly or logarithmically along the x and y dimensions,
respectively. The type of the element specified by name must be a
four-node planar element.
Brick Grids
A brick-grid-generator specifies the generation of solid brick elements
within a three-dimensional grid. The generator has the following
syntax.
[ start = triple ]
[ end = triple ]
[ x-number = expression ]
[ y-number = expression ]
[ z-number = expression ]
[ x-rule = linear | log ]
[ y-rule = linear | log ]
[ z-rule = linear | log ]
[ element-type = name ]
The start and end triples define the diagonally opposite corners of the
grid. The x-number, y-number, and z-number assignments specify the
number of elements along the x, y, and z dimensions respectively.
Similarly, the x-rule, y-rule, and z-rule assignments specify whether
the elements are to be generated linearly or logarithmically along the
x, y, and z dimensions respectively. The type of the element specified
by name must be an eight node solid element.
Triangular meshes
A triangular-mesh-generator specifies the generation of triangular
elements within a two-dimensional mesh. The generator has the
following syntax.
[ tolin = expression ]
[ angspc = expression ]
[ angtol = expression ]
[ dmin = expression ]
[ kappa = expression ]
[ min = expression ]
[ max = expression ]
[ boundary = [ pair-list ] ]
[ hole = [ pair-list ] ]
[ element-type = name ]
where a pair has the following form:
( expression , expression )
The tolin, angspc, angtol, dmin, kappa, min, and max parameters control
the specifics of the mesh generation and are discussed in the user’s
guide. The element type specified by name must be a planar, triangular
element. The boundary assignment specifies the boundary points of the
mesh which must be given in counter-clockwise order. The pair-list is
a sequence of pairs. A hole assignment specifies a hole within the
mesh and similarly the points must be given in counter-clockwise order.
Unlike other assignments, a hole assignment does not overwrite a
previous assignment but instead adds to it. Thus, more than hole can
be specified by repeating the hole assignment as many times as
necessary.
AUTHOR
The corduroy file format was developed by Jason I. Gobat
(jgobat@mit.edu) and Darren C. Atkinson (atkinson@ucsd.edu).
SEE ALSO
corduroy(1fe), felt(4fe).