corduroy

CORDUROY(4fe)               Finite Element Package               CORDUROY(4fe)



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).



Version 2.30                        5/19/94                      CORDUROY(4fe)