Mesh Object Definition

The data structure which contains the information necessary to define a mesh is called a Mesh Object. A Mesh Object consists of attributes that define the mesh identified by a mesh object name. Attributes are updated by LaGriT routines and can be modified by the user. Use the command cmo/status to see the attributes for all mesh objects, or use cmo/status/cmo_name for the attributes of the mesh object identified by that name.

The default Mesh Object can be expanded by adding user defined attributes with cmo/addatt. User attributes can be removed with cmo/delatt. Default mesh object attributes can not be removed. Some of the LaGriT routines add attributes to the mesh object. The user should never try to add an attribute whose name is already listed as a mesh object as these are reserved as mesh object attribute names (See below).

The value of many of the scalar attributes can be changed by the cmo/setatt/ command. For instance, cmo/setatt/cmo_name/epsilonl/1.d-9 will set the attribute epsilonl to 1.d-9 for the mesh object named cmo_name.

Mesh Object Attributes

These are default attributes for a Mesh Object:

• name (character*32 – mesh object name, this is the unique identifier for any particular mesh object)

• scalar (integer – defined to have value 1)

• vector (integer – defined to have value 3)

• nnodes (integer – number of nodes in the mesh)

• nelements (integer – number of elements in the mesh, e.g. triangles, tetrahedra)

• nfaces (integer – number of unique topological facets in the mesh, e.g. number of edges in 2D or number of element faces in 3D). This is not maintained but may be used by certain commands or by the user.

• nedges (integer – number of unique edges in mesh) This is not maintained but may be used by certain commands or by the user.

• mbndry (integer – value signifying that if the node number is greater than mbndry then the node is a boundary node; default 16000000) This value must be greater than 48 * nnodes and may be reset by connect (for an example of usage see Mesh Object Connectivity).

• ndimensions_topo (integer – topological dimensionality; 1, 2 or 3. i.e. a non-planar surface would have ndimensions_topo = 2 and ndimensions_geom = 3.)

• ndimensions_geom (integer – 1, 2 or 3 for dimension of geometry; default 3)

• nodes_per_element (integer – value dependent on type of mesh; e.g. for tetrahedral mesh the value will be 4)

• edges_per_element (integer – value dependent on type of mesh; e.g. for tetrahedral mesh the value will be 6)

• faces_per_element (integer – topological number of facets per element (i.e. in 1D this number is always 2, for 2D use the number of edges of the element, for 3D use the number of faces of the element; e.g. for tetrahedral mesh the value will be 4)

• isetwd (integer array containing pset membership information, see pset command definition)

• ialias (integer array of alternate node numbers, i.e. for merged points)

• imt1 (or imt) (integer array of node material values, must be values greater than zero )

• itp1 (or itp) (integer array of node types if type > 20 node will be invisible) These values can be updated anytime with the resetpts/itp command. Use rmpoint/compress to remove dudded nodes from the mesh object.

icr1 (or icr) (integer array of constraint numbers for nodes; the value of this array is an index into the icontab table of node constraints described later in this section)

isn1 (or isn)(integer array of child, parent node correspondence)

Points on material interfaces are given itp1 point type 41 (parent). One child point is spawned for each material meeting at the parent point. The isn1 field of the parent point will contain the point number of the first child point. The isn1 field of the first child will contain the point number of the next child. The isn1 field of the last child will contain the point number of the parent. The point types of the child points will be 2, 12, 13, 15 or 19 depending on whether the interface point is also on an exterior boundary. This parent, child relationship is established by the settets command and is undone by the resetpts/parents command.

xic, yic, zic (real arrays of node x, y, z coordinates)

itetclr (integer array of element material values, should be greater than zero)

itettyp (integer array of element shape values. For an example of usage see Mesh Object Connectivity). See element conventions at Supported element types

xtetwd (integer array containing eltset membership information, see eltset command definition )

itetoff (integer array index into itet array list for elements, for an example of usage see Mesh Object Connectivity)

jtetoff (integer array index into jtet array list for elements, for an example of usage see Mesh Object Connectivity)

itet (integer array of node vertices for each element, for an example of usage see [Mesh Object Connectivity (meshobjcon.md#itet))

jtet (integer array of element connectivity, for an example of usage see Mesh Object Connectivity)

ipolydat, vor2d, vor3d (character yes or no, default yes. These flags include data when writing GMV output files, these can decrease the file size but limits the information written.) ipolydat writes polygon data, vor2d writes voronoi and median cells for 2D, vor3d writes voronoi and median cells for 3D meshes. See dump/gmv

dumptype (character with default set to binary, type of gmv file to write)

epsilon (real value of machine epsilon which will be calculated by the code.)

epsilonl (real value of smallest edge length that the code can distinguish and will be set internally by the code, see setsize )

epsilona (real value of smallest area that the code can distinguish and will be set internally by the code )

epsilonv (real value of smallest volume that the code can distinguish and will be set internally by the code )

ipointi, ipointj (integer value with the node number of the first node and last node of the current set of nodes, used by the indexing syntax for point sets: / 0,0,0 / pset)

idebug (integer value indicating level of debug output, flag values greater than 0 produce increasing levels of output with 5 or greater generating the most information )

itypconv_sm, maxiter_sm (integer values used by the smooth routines. maxiter_sm has default 25 and are the number of smoothing iterations in smooth and radapt )

tolconv_sm (real value used by the smooth routines)

nnfreq (integer value with default 1, flag to control reconnection after refine This is set to zero to turn off reconnection.)

ivoronoi (integer value with default 1, flag to control reconnection criterion. See recon) )

+1 means restore delaunay
-2 means improve geometric quality of the elements
+2 means adaptive reconnection with user supplied routine
+5 means disable all reconnection

iopt2to2 (integer value with default 2, flag to contol boundary flips during reconnection. See recon) )

0 = exterior boundaries
1 = interfaces
2 = exterior boundaries and interfaces
3 = all

velname, densname, presname, enername (character specialized attribute names for velocity, density, pressure, and energy variables. Default names set to vels, ric, pic, and eic. )

xmin, xmax (real value with minimum and maximum x coordinate of nodes in the mesh. Values are set internally and by setsize )

ymin, ymax (real value with minimum and maximum y coordinate of nodes in the mesh. Values are set internally and by setsize )

zmin, zmax (real value with minimum and maximum z coordinate of nodes in the mesh. Values are set internally and by setsize )

kdtree_level (integer with default value 0. This is the resolution level, number of octree refinements where 0 means terminal nodes contain 1 0 means terminal nodes contain 1 member.)

max_number_of_sets (integer with default value of 32. This is the number of pset and eltset allowed for a single mesh object.)

number_of_psets, number_of_eltsets (integer value with the number of psets and eltsets in the mesh.)

psetnames, eltsetnames (character are the set names for pset and eltset)

geom_name (character with default set to -defaultgeom-. This is the name of geometry associated with this mesh.  See geom))

fset_names (integer value with the number of face sets in the mesh.)

number_of_fsets (character are the set names for fset.)

The above are the default attributes for a mesh object. Multiple mesh objects can be defined, all with their own attributes and attribute values. Added attributes will be listed after this list of defaults if they have been added. The current state and list of attributes of a mesh object can be displayed by using the command cmo/status.

Mesh Object Attribute Definition

Each attribute (either default attribute or added attribute) in a mesh object has the following defined:

• name  character Attribute name, case sensitive.

• type  character with default VDOUBLE. Attribute type is one of the following, case ignored.

    INT- Integer
    REAL - Real number
    CHARACTER - character string (length 32)
    VINT - Vector of integer
    VDOUBLE - Vector of real (this is the default)
    VCHAR - Vector of character strings

• rank  character with default scalar. This is the attribute rank set by an attribute for this Mesh object.

• length  character with default nnodes. This is the attribute length set by an attribute for this Mesh object.

• interpolation   character with default linear. This is the interpolation option for routines to use:

    linear   - Linear interpolation  (this is the default)
    constant - Constant value
    sequence - Set to the node number
    copy     - Copy values 
    user     - User provides a subroutine named user_interpolate
    log      - Logarithmic interpolation
    asinh    - Asinh interpolation
    min      - Set to the minimum
    max      - Set to the maximum
    incmin   - Set to the minimum plus one (vint attribute only)
    incmax   - Set to the maximum plus one (vint attribute only)
    and      - 'and' the bits
    or       - 'or' the bits

• persistence    character with default temporary. Attribute persistence where permanent can not be deleted, temporary can be deleted.

• ioflag character with default alg. These letters are IO flags to define what type of common output files this attribute can be written to. By default, the dump command will write all attributes, this flag can be used to limit which attributes are dumped.

    a - write this attribute on avs dumps
    g - write this attribute on gmv dumps
    f - write this attribute on fehm dumps
    l - write this attribute on LaGriT dumps
    L - Do Not write this attribute on LaGriT dumps
  

• default real default is 0.0. This is the attribute value to initialize the data with.