Meshing Field Functions Reference

This section contains a list of field functions that are related to meshing.

Surface Mesh Field Functions

Several field functions are made available in Simcenter STAR-CCM+ as a result of importing parts or using the surface remesher.

Area

Displays the area of the cell faces. Only available for surface meshes.

Magnitude: Displays the absolute value of area.
Laboratory: Displays the value of area normal to the i, j, or k directions.

Centroid

See Space Field Functions Reference.

DeviationDistance.AutomatedMesh

Compares the latest surface that is displayed in the scalar scene to an earlier description that is created from the automated mesh operation. Displays how far the surface in the scene deviates from the earlier description.

DeviationDistance.Root

Compares the latest surface that is displayed in the scalar scene to the root description and displays how far the surface in the scene deviates from the earlier root description.

EdgeLength

Displays the average edge length on faces. Only available for surface meshes.

FaceQuality

Displays the face quality value on faces, where 1.0 is the highest quality and 0.0 is the lowest quality. Only available for surface meshes.

FreeEdges

Displays any free edges on the surface. Only available for surface meshes.

NonmanifoldEdges

Displays any non-manifold edges on the surface. Only available for surface meshes.

Position

See Space Field Functions Reference.

SurfacePatch

Displays each surface patch as a unique number. Only available for surface meshes.

Volume Mesh Field Functions

Several field functions are made available in Simcenter STAR-CCM+ as a result of mesh model selections or meshing operations.

Area

The Area field function displays the area of the cell faces. Area can be shown as either a Magnitude or as Laboratory coordinate values. From Simcenter STAR-CCM+ version 10.02, you can also run the Area field function on an unmeshed surface.

Magnitude: Displays the absolute value of area.
Laboratory: Displays the value of area normal to the i, j, or k directions.

Boundary Index

This field function displays the index number that is associated with the boundaries. Each boundary has a unique boundary index that distinguishes it.

Boundary Sliver Cell Indicator

This field function indicates cells that are “boundary slivers”. Boundary slivers are flat cells on the outer boundaries of the solution domain that can be removed without affecting the topology of the mesh.

A value of 0 indicates that the cell is not a boundary sliver cell, and a value of 1 indicates that the cell is a boundary sliver cell. (Available when the Cell Quality Remediation model is used). For more information, see Cell Quality Remediation Field Functions Reference.

Cell Aspect Ratio

This field function is used to identify regular polygonal cells from skewed or stretched cells. A value of 1 indicates that the cell is a regular polygon, and a value close to 0 would represent a highly stretched cell.

For more information, see Space Field Functions Reference.

Cell Index

This field function displays the index for each cell. The index is only unique within the portion of the mesh for a given region on the local partition. So if you have R regions that are partitioned across P processors there are R*P cells with index 0 (assuming enough cells to allocate at least one per region per partition). It is not an ID, it is an offset.

Cell Quality

Cell quality is a function that is determined from the relative geometric distribution of the cell centroids of the face neighbor cells and of the orientation of the cell faces. Generally, flat cells with highly non-orthogonal faces have a low cell quality. A cell with a quality of 1.0 is considered perfect.

A degenerate cell has a cell quality approaching 0. Depending on the physics that has been selected, the cell quality of a cell can be fairly low and still provide a valid solution. However, poor cell quality is likely to affect both the robustness and accuracy of the solution. Cell quality is only defined for three-dimensional meshes.

See Mesh Quality: Cell Quality.

Centroid

The centroid is the location vector of the center of mass of the volume (or shell). The center of mass can be displayed as a Magnitude or by Laboratory coordinates. For more information, see Space Field Functions Reference.

Magnitude: Displays the absolute location of the center of mass.
Laboratory: Displays the location of the center of mass in either the X, Y, or Z direction.

Chevron Quality Indicator

This field function identifies chevron cells. Chevron cells are pairs of thin slender cells which meet at a common face at an angle such that the line joining the cell centers does not pass through the common face. Chevron cells are marked as 1.0 and every other cell as 0.

See Mesh Quality: Chevron Quality Indicator.

Element Type

The element type identifies the specific star cell topology for each cell. Each number corresponds to a different type of topology, as shown below:

One Dimensional

3—STAR_LINE_CELL
21—STAR_QUADRATIC_EDGE

Two Dimensional

5—STAR_TRI_CELL
7—STAR_POLYGON_CELL
9—STAR_QUAD_CELL
22—STAR_QUADRATIC_TRIANGLE
23—STAR_QUADRATIC_QUAD

Three Dimensional

10—STAR_TET_CELL
12—STAR_HEX_CELL
13—STAR_WEDGE_CELL
14—STAR_PYRAMID_CELL
24—STAR_QUADRATIC_TETRA
25—STAR_QUADRATIC_HEXAHEDRON
26—STAR_QUADRATIC_WEDGE
29—STAR_TRIQUADRATIC_HEXAHEDRON
41—STAR_UNIDENTIFIED_CELL
42—STAR_POLYHEDRON

Face Index

Face index displays the partition-local index for each boundary face.

Face Type

Face type displays the number of vertices per face. For example, a triangular face has a Face Type of 3 and a hexagonal face has a Face Type of 6.

Face Validity

Face validity is an area-weighted measure of the correctness of the face normals relative to their attached cell centroid. In a good quality cell, the face normals point away from the cell centroid. In a cell with bad face validity, one or more face normals point towards the attached cell centroid. A face validity of 1.0 means that all face normals are correctly pointing away from the centroid. Values below 1.0 mean that some cell face normals point towards the centroid, indicating some form of concavity. Values of below 0.5 signify a negative volume cell.

See Mesh Quality: Face Validity.

Interface Parent Face Index

This field function is the offset of the parent face for each direct boundary interface boundary face. Each face on a direct boundary interface boundary is a piece of an intersection of one face from each of the contributing boundaries. This index identifies those faces from the contributing boundaries.

Least Squares Quality

Least squares quality is an indicator of the quality of a cell that is based on the physical location of a cell centroid relative to the cell centroid locations of its face-neighbors. (Available when the Cell Quality Remediation model is used).

See Mesh Quality: Least Squares Quality.

Partition

The primary partition that the cell/face/vertex is on. When a simulation is run in parallel, the regions are decomposed across the number of processors such that each cell is allocated to a primary partition.

Periodic Index

Repeating interfaces can require multiple passes to intersect all faces. For example, a rotor-stator (sliding interface) case intersects once in situ, rotates/translates one side by the periodic transform and intersects again, and repeats until all faces are consumed. For a given intersected face, this value reports the number of steps that were required until it was matched. So it indicates how many multiples of the periodic transform must be applied to align it with the other side of the interface.

Position

This field function displays the position of the vertices relative to the origin. Position can be displayed as a Magnitude or as Laboratory coordinates. For a cell, the position is returned as the average of the positions of the vertices of the cell. For more information, see Space Field Functions Reference.

Magnitude: Displays the absolute position.
Laboratory: Displays the position in either the X, Y, or Z direction.

Prostar Face Id

When a face on an imported STAR-CD mesh has been assigned a boundary, this field function returns the index of the original pro-STAR boundary. In pro-STAR, this number would be plotted in response to the NUMB,BOUND,ON command.

Prostar Cell Id

This field function contains the original pro-STAR cell number for the imported STAR-CD mesh. In pro-STAR, this number would be plotted in response to the NUMB,CELL,ON command.

Prostar Cell Type

This field function contains the pro-STAR cell table index number for the imported STAR-CD mesh. In pro-STAR, this number would be plotted in response to the NUMB,TYPE,ON command.

Radial Coordinate

If an axis is defined, this field function provides the distance from the axis.

Region Index

This field function contains the region index. Each region has a unique region index that distinguishes it from other regions.

Skewness Angle

This field function contains the skewness angle of the cells. It indicates whether the cells on either side of a face are formed in such a way as to permit diffusion of quantities without these quantities becoming unbounded. To reduce the impact on robustness, avoid skewness angles greater than 85 degrees.

Unmatched Edge Count

This field function displays any unclosed cells. A topologically closed volume cell consists of edges that are connected to exactly two faces, and faces with normals pointing outwards. If a cell is missing a face or the outward normals are not consistent, then it is considered unclosed and invalidates the mesh.

Volume

This field function contains the volume of each cell.

Volume Change

This field function describes the ratio of the volume of a cell to that of its largest neighbor. A value of 1.0 indicates that the cell has a volume equal to or higher than its neighbors. A large jump in volume from one cell to another can cause potential inaccuracies and instability in the solvers. Investigate cells with a volume change value of 1e-05 or below as they can be considered suspect.

See Mesh Quality: Volume Change.

Zero Face Area Indicator

This field function has the value of unity if the area of any of the faces approaches zero; otherwise it has a value of zero. It is used to diagnose potential mesh problems. (Available when the Cell Quality Remediation model is used). For more information, see Cell Quality Remediation Field Functions Reference.

Prism Layer Mesher Field Functions

Several field functions are made available in Simcenter STAR-CCM+ as a result of mesh model selections or meshing operations.

First Prism Layer Height: Displays the thickness of the cells in the first prism layer.
Prism Cell Thickness: Displays the thickness of each cell within the prism layers.
At the boundary faces from which the prism layers grow, the value of this field function is equal to the prism layer total thickness.
Prism Layer Cells: Displays all the cells within the prism layers.
Prism Layer Number: Describes in which layer cells are located. . 1 indicates the cell is in the first layer of the prism layers.
All the boundary faces, from which the prism layers grow, obtain the number of total prism layer.

Note	Prism layer field functions are not available for imported meshes and meshes generated using the Turbomachinery Mesher. For prism cells generated using the Directed Mesh, Tetrahedral Mesher, Advancing Layer Mesher, these field functions are available but may be less accurate.

Finite Element Mesh Field Functions

Several field functions are made available in Simcenter STAR-CCM+ as a result of using finite element models. They are used to diagnose potential mesh problems.

Fe Cell Quality Angle Skewness: This field function describes how narrow the narrowest angles of the cell are. The value ranges from 0 to 1; 0 is a bad cell. See Angle Skewness.
Fe Cell Quality Aspect Ratio: This field function describes the ratio of between the longest and shortest edges of a cell. The value ranges from 1 to infinity; A value much greater than 1 is a bad cell. See Aspect Ratio.
Fe Cell Quality Middle Point Deviation: This field function describes how far the mid-side vertex is from the diagonal between corner vertices. The value ranges from 0 to infinity. A good cell has a value of less than 0.25. Inverted cells have a value of -1. See Middle-Point Deviation.
Fe Cell Quality Shape: This field function reports a quantity based on the Jacobian determinant of the cell. The value ranges from 0 to 1; higher is better. See Shape.
Fe Cell Quality Warp: This field function reports the maximum distance of the cell face vertices from the face plane. The value ranges from 0 to infinity. A good cell has a value of less than 0.5. See Warpage.
Fe Invalid Element Indicator: This field function reports if any of the finite elements have a negative Jacobian determinant at the element vertices. The value ranges from 0 to 1; 1 is an invalid element. See Shape.