The process of setting up properties is usually quite simple and relies on the concept of cell identity and the consequent use of the cell table, as discussed under“Cell types” on page 2-37of the Meshing User Guide. The cell table can be defined using pro-STAR’s Cell Table Editor, accessed by clicking the CTAB button on the left-hand side of the main pro-STAR window.
All cells in the mesh can be indexed and differentiated in various ways with the aid of an entry in the cell table. This enables the user to specify a
• cell table index
• cell type
• material number
• colour table index
• porosity index
• spin index
• group number
• surface lighting material index
• processor number
• conduction thickness
• radiation switch
• initial free-surface identifier
• identifying name
for a set of cells, as shown in the dialog below. The meaning of the various parameters that may be set in this table is described in“Cell properties” on page 2-38 of the Meshing User Guide.
The Cell Table
The rules governing the use of the cell table are as follows:
• All entries in the table are identified by an index, listed under the Table # heading in the editor’s scroll list. A new entry is set up by clicking on the next available number in the list and then specifying the relevant cell properties.
• Every cell in the model is associated with a cell table index.
• All cells linked via a common index belong to a common Cell Type (Fluid, Solid, Baffle, etc.), selected from the editor’s pop-up menu.
• Different materials are identified by separate material property numbers, typed in the Material Number text box.
• The default cell table index is number 1 and is associated with a fluid whose material number is 1.
• By default, material number 1 refers to air properties at standard conditions.
• Cell indexing normally differentiates the cells’ material type. However, it can also be used purely for visual and/or selection purposes. Thus, in the diffuser model shown inFigure 3-1 there is a single material number (no. 1),
corresponding to the one and only domain in the model, but the cells can be indexed to different colours or different types of surface shading (seeChapter 4 of the Meshing User Guide). This is done by typing different values in the Color Table Index or Lighting Material text boxes, respectively.
• Colour selection is facilitated by clicking the multi-coloured button next to the Color Table Index box. This opens a Color Palette panel where the desired colour is selected by simply clicking the appropriate square. The
corresponding colour number is then automatically entered into the box.
• Another possibility is to index cells on the basis of a common group number, typed in the Group Number text box. This groups together all cells belonging to a particular ‘object’, e.g. a distinct portion of the mesh. Such objects might typically be generated with the help of an external CAD package and
Commands: CTABLE CTNAME CTMODIFY CTLIST
CTDELETE CTCOMPRESS
The Cell Table
imported into pro-STAR using IGES or VDA data files. Group numbers are normally generated automatically as part of the data import function (see
“Importing Data from other Systems” on page 3-1 of the Meshing User Guide).
• Cell table entries can be further identified by a name, typed in the Name box.
A cell table definition is confirmed by clicking the Apply button.
Figure 3-1 Cell indexing to implement differentiation by cell colour
Cell table entries may be displayed at any stage of the pro-STAR session by clicking CTAB on the main window. Any identifier, index, or reference number used in a cell table entry may be changed to a different value simply by selecting the entry in the Cell Table Editor’s scroll list and making the required changes.
Cell table entries may also be deleted by clicking the Delete button. Note that all cells indexed to this entry must be deleted or changed to a different index before the table entry itself can be deleted. Tables that contain deleted (or undefined) entries such as this may be cleaned up by clicking the Compress button. This removes all redundant entries and re-numbers the remaining ones.
Cell indexing
Cells are assigned an identity (cell index) using the Cell Tool shown overleaf. This may be done in two ways:
1. Implicitly, by taking on the index that is active at the moment of their creation. The active cell type can be changed at any time by highlighting the type required in the Cell Table list displayed by the Cell Tool and then
clicking the Set Active Type button. The selection is indicated in the list by a letter ‘A’ against the active type.
2. Explicitly, by collecting together a group of cells and then changing their identity to the currently-active type. This can be done by:
(a) Pointing at the desired cells with the screen cursor — choose option Modify Type > Cursor Select. The action is terminated by clicking the Done button displayed on the plot.
(b) Changing all cells contained within a polygon drawn on the screen with the screen cursor — choose option Modify Type > Zone. The action is terminated by clicking on
i) the same point twice to complete the polygon;
Cell index 1 Cell index 2 Cell index 3 Colour 2
Colour 3
Colour 4
The Cell Table
ii) the Close button displayed, to let pro-STAR complete the polygon;
iii) the Abort button displayed, to abort the selection operation.
(c) Changing all surface cells encountered when searching from a starting position given by a ‘seed’ vertex (see the description on page2-49 of the Meshing User Guide). This can be done by choosing option Modify Type
> Surface (New Edge Vertex Set) (or Surface (Current Vertex Set)).
The ‘seed’ vertex is selected with the screen cursor.
(d) Changing all cells in the current cell set — choose option Modify Type >
Cell Set.
Another method of making changes is via the Cell List dialog, shown overleaf. This may be displayed by clicking the Cell List button on the Cell Tool or choosing Lists
> Cells from the main menu bar. The cell or cell range to be changed must first be selected on the list. To change the associated cell type, click Change Type, choose a different cell table index on the displayed Change Cell Table box and then click Apply.
Commands: CTYPE CCROSS CFIND CZONE CTCOMPRESS