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Archive Pointwise UGM
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Gridgen Version 13.3.4 - 07 February 2000Gridgen Version 13.3 introduces many new features and one of the most important is the ability to generate hybrid grids that use prism and pyramid cells. Pyramids are automatically created whenever quadrilateral (structured) domains are used in the creation of an unstructured block's face. Prisms are created by extruding triangular meshes. Extrusion methods also represent a significant new capability in Gridgen Version 13.3. Other than extruding prism layers as described above, the hyperbolic PDE extrusion method has been made quite a bit more robust and complemented with normal, translational, rotational, and path-based algebraic extrusion methods. Domains may now be created in a highly automated manner using the new On DB Ents command. Combined with the new capability to create domains with holes and the wider variety of unstructured grid attribute defaults, a complex surface mesh on a NURB model can be very rapidly created. In order to ensure that the domains automatically created using On DB Ents fit together in a seamless manner the new Merge command is also automatically applied. Merge may also be applied manually and allows you to trim, split, and merge coincident and overlapping connectors. The last two notable features include changes to the ReDistribute command for connectors that lets you work on multiple connectors at the same time and the new MaxDev and MaxAng connector dimensioning and distributing tools that let you insert grid points into a connector to minimize the faceting of the connector shape. Setting DefaultsGridgen's tolerancing scheme has been expanded to improve the ability to generate grids on sloppy CAD models. There are now four tolerance values in the Defaults menu as described below.
Two new defaults are available for controlling the dimension of and
distribution of grid points along new connectors: Con Dim
MaxDev and MaxAng. If either of these defaults is
enabled, every new connector is dimensioned initially according to
the settings of the Con Dim dimen and avg
The Unstrdom Interior Pts toggle button allows you to disable the initialization of unstructured triangular meshes during the domain creation process in order to save CPU time. Presumably you would do this so that you could customize the unstructured grid attributes for all domains just created and initialize them all at once, balancing the interactive speed of creating domains against the hands-off triangulation. Several unstructured grid solver attributes (labeled UnstrDom andUnstrBlk) may now be set in the Defaults menu for use in triangulating new unstructured domains and blocks, respectively.
Graphical User InterfaceGridgen's on-line help feature now uses your HTML browser to display a context-sensitive version of the Gridgen User Manual. Previously fatal errors are now captured by Gridgen's new exception handling mechanism, giving you the opportunity to save your work before exiting the code. A new feature called "drawing lag" has been added to the Display Commands menu with the Demote button. If the value of the drawing lag parameter is non-zero, the Display window image is drawn in a sparse mode during image manipulation (i.e. panning, zooming, and rotation). Sparse mode turns off the display of domain grid points and draws database entities as outlines. The value of the drawing lag parameter, in the range between 0 and 10, indicates the delay between the time when the image manipulation device is released (i.e. when you let go of the mouse button) and the time when the image is drawn in its normal mode. The time delay increases with the value of the drawing lag. A large value of drawing lag prevents the image from being redrawn unnecessarily between successive manipulations. Pressing the space key will also cause the image to be redrawn. Mouse warping (when Gridgen moves the cursor for you to a menu button) may now be disabled using the Warp toggle button on the Display menu. For consistency with previous Gridgen versions, mouse warping is on by default. The new Show EnbldDB toggle button in the Display commands menu allows you to easily turn off the display of all database entities without having to disable them. When the EnbldDB button is disabled, enabled databases are not drawn while in the Display commands menu and are drawn in a sparse mode elsewhere. Enabled database entities are displayed by default. The Display menu's new LeftPk toggle button allows you to change which mouse button Gridgen uses for menu button and Display window item picking. Gridgen uses the right mouse button for picking by default. Turning on the LeftPk toggle causes the left mouse button to be used for picking - the right mouse button is then used for image panning. When picking multiple items from the Browser, the list now automatically scrolls up or down when the right mouse button is held down and the cursor is above or below the Browser, respectively. The new By Text button in the Browser menu allows you to enter a text string and all items having that text in their Browser text will be picked. The new Page button in the Browser menu lets you pick all items on the current page of the Browser. Text input mode may now be aborted using the escape hot key in addition to r and R. Any point visible in the Display window, including grid points but excluding database render points, may now be selected as the rotation point using the Display menu's Rot Pnt command. Also, the rotation point may now be picked at any time (no need to be in the Display menu) by positioning the cursor over the desired rotation point in the display window and pressing control - right mouse. When using the latter method the coordinates of the picked point are displayed in the message window. Furthermore, if you press shift - right mouse the message window also displays the straight line distance from the previously selected point to the current selected point. Importing and Exporting FilesThe format of the Gridgen (.gg) and composite database (.dba) files was changed to accommodate new features. On-going improvements to the IGES import command improve Gridgen's ability to import CAD models. However, since this improvement can result in entity names that are different from the names that result from import into Gridgen Version 13.2, we recommend that all grids currently in work with Version 13.2 be completed in Version 13.2. New grids requiring IGES or existing grids not requiring IGES files should be worked in Version 13.3. Creating ConnectorsDuring connector segment creation and editing, the Move + to Screen Center command now works for database constrained segments. If the location of the screen center is outside the current database entity's boundaries, the 3D cursor is moved to the closest point on the entity to the screen center. Creating DomainsUnstructured domains with multiple edges (i.e. holes) can now be created, both by the On DB Ents domain creation command and by the Assemble Edges method. This new feature is the surface grid analogy of Gridgen's multi-faced unstructured blocks in which the first face is the block's outer boundary and any additional faces are the inner boundaries of holes. The first edge in a multi-edged unstructured domain is always the outer boundary. Any additional edges are inner boundaries around holes. Furthermore, the direction of the inner-edges (i.e. the orientation of the hole boundaries) must all be consistent and opposite of the outer boundary's (first edge's) orientation. This may be adjusted on an edge by edge basis during domain creation by pressing the Reorient Edge button. An On DB Ents command has been added for creating domains. It is the surface equivalent of the same-named command for connector creation and allows either structured or unstructured domains to be created. You pick any or all enabled surfaces (trimmed and untrimmed) in the database and then Gridgen does the following.
A toggle button called Auto Complete was added to the domain assembly menu. When this toggle button is enabled Gridgen attempts to finish the domain for you automatically once the first two edges are added. Creating BlocksThe commands available for creating block faces in the Assemble Face have been significantly expanded. The new tools, all labeled Pick, are:
Grid Methods for ConnectorsThe ReDimension command in the Connector Modify menu may now be applied to more than one connector at time, for all connectors not used in structured domains. In order to make this command work well with all of the new connector dimensioning and distributing attributes, this command's menu button layout was changed as described below.
A new distribution function (available through the Select Distrib. Func. button in the Connector Modify ReDistribute command) is available for connectors that allows application of the new maximum deviation and maximum turning angle criteria. This new function, called MaxDev + MaxAng , allows you to enter values for the maximum deviation of the discrete connector from the segment shape, the maximum turning angle allowed between adjacent grid points along the connector, and a third parameter designating whether or not the current beginning and ending spacing constraints should be kept or released. Note that unlike implementations of this feature elsewhere in Gridgen, the connector dimension is NOT changed when this feature is applied through the ReDistribute command. This means that the deviation and turning angle limits you specify will not be enforced exactly, but the general trend in grid point clustering will be applied. Furthermore, if you choose to retain the beginning and ending spacing constraints when applying this distribution function be aware that the level to which the limits will be enforced is seriously degraded. The ReDistribute command for connectors may now be applied to more than one connector at a time. Focus Next and Prev buttons allow you to change the focus connector whose information is displayed in the Blackboard. Apply to Focus and All radio buttons specify whether the distribution attributes you choose should be applied only to the focus connector or to all picked connectors, respectively.
You now have the option to disable the display of the focus
connector's control points during grid point distribution by
disabling the Grid Methods for Unstructured Domains and BlocksPyramid elements are now created in unstructured blocks whenever and wherever structured domains are added to a block's face. Several pyramid attributes are available as described below.
Grid Extrusion MethodsAn entire new suite of tools for domain and block creation called Extrude has been added. The hyperbolic solver for structured grids from Gridgen Version 13.2 forms the basis of the new Extrude command. In fact, you'll notice that the hyperbolic method is no longer listed as a grid solver but is now found as an extrusion method under Create. Highlights of the extrusion methods are listed below.
MiscellaneousA new suite of tools for finding and removing coincident and overlapping connectors has been added. These tools are automatically applied by the On DB Ents connector and domain creation commands. The tools may also be applied from the Connector menu and during block face creation. The suite of tools includes the following commands.
The Name command for database entities now allows you to select multiple database entities and Gridgen automatically renames all of them by appending "-1", "-2", "-3", etc. to the text string you type in. Diagnostic FunctionsAspect ratio and skewness measures were redefined for the Examine command. The Examine command was expanded to be able to handle hybrid mesh cells (i.e. prisms and pyramids). Constant x, y, and z reference planes were added for structured block viewing. Constant i, j, or k reference planes are also available for prism blocks. Physical cutting planes now cut all examined blocks in global mode. Analysis Software InterfacesExport filters for CFX 5, Exodus II, Tetrex, and CFDSHIP-IOWA were added. Prism and pyramid export was added to Star-CD, Fluent, CFX-5, and GUST. The block number is now written as a volume condition (the volumetric equivalent of a flow solver boundary condition, what an FEA solver might call a material property) for Star-CD, Fluent, and CFX-5. SPRsSPR 13.0190Fixed a big problem with the calculation of index ranges for interblock connections for the WIND export filter. SPR 13.0203The Windows version of Gridgen now handles ASCII files the same whether they've been created on Unix or Windows. SPR 13.0206Repaired incorrect formatting of FLUENT .cas files for 2D triangular meshes. SPR 13.0211A problem with the rendering triangulator for trimmed surfaces that caused IGES import to fail has been fixed. SPR 13.0212The elliptic solver no longer fails on Windows when applied to domains with poles. SPR 13.0214Changed the IGES reader to allow trimming curves to be slope discontinuous. In this particular SPR the trimming curves had interior 90 degree bends. SPR 13.0215Changed the dependency checking during IGES import of trimmed surfaces to ensure that the trimmed surface would not be created if any of its constituent entities (un-trimmed surface and trimming curves) had import errors. SPR 13.0216It is no longer possible to select an uninitialized (empty) tetrahedral block for export. The volume mesh must be initialized explicitly first using the Run Solver Unstructured command. SPR 13.0220Fixed a problem with the GCL implementation of the connector dimension default. SPR 13.0221When run from a GCL script the elliptic solver was not updating the connector shape on internal boundaries with floating boundary conditions; this has been fixed. Also fixed a GCL problem involving export of a connector's grid points. SPR 13.0224Gridgen's point picking in 2 Point Connector creation was modified to ensure that regardless of the render mode only the end points of database curves are pickable. SPR 13.0225Repaired the formatting of the menu title in the domain elliptic solver's boundary condition menu. SPR 13.0226Added support for forms 11, 12, and 13 of the IGES 106 (copious data) entity. SPR 13.0230Enhanced the IGES reader by changing the manner in which gaps in trimming curves are judged. In addition to the normal global tolerancing procedure Gridgen now takes into account the relative sizes of the gap and the trimming curve for a local effect. This makes the IGES reader more tolerant of trimming curves with gaps. SPR 13.0232Fixed a problem with the rendering of circular arc connectors that made grid points appear to be off the connector. SPR 13.0234Repeated splitting of a database surface could result in a failure; this has been fixed. SPR 13.0236Gridgen now locks a tetrahedral block's bounding domains automatically when the unstructured solver is run to ensure that the tetrahedra are not purged during Gridgen file import. SPR 13.0237The quality of triangular cells in unstructured domains on NURB surfaces generated by the Parametric Triangulation (i.e., generated in the parametric space of a single NURB surface) has been improved by performing an implicit reparametrization of the NURB prior to generating the mesh. SPR 13.0238Fixed a tolerancing problem that would move grid points off connectors during projection when the connector spanned multiple database surfaces. SPR 13.0239An HP-specific IGES import problem that would cause Gridgen to freeze that been repaired. SPR 13.0244Fixed a corrupt record header in Fortran unformatted export of domain grid points. SPR 13.0249Added a special check to the domain logic for finding poles to prevent Parametric Fit from being applied. SPR 13.0252PostScript image export had inadvertently been left out of the Windows version. It's back. SPR 13.0253Added Windows-specific code to domain and block grid export to make sure that 3 digit exponents are not used. SPR 13.0255Fixed a formatting error for WIND's "Bleed" boundary condition. SPR 13.0257Improved the Block Split command's ability to work with block's containing poles. SPR 13.0259Gridgen now finds and renames entities in an IGES file whose names (from the 406 entity) are a single space. SPR 13.0261Fixed a cell numbering bug in NASTRAN grid export. SPR 13.0270During database file import, any file with a non-standard extension is assumed to be IGES. If IGES import fails the database file attributes menu should be displayed so that you can specify the correct file type. This wasn't happening in all cases but has since been fixed. SPR 13.0273A bug in computing interblock connections during FV-UNS grid import has been fixed. SPR 13.0275Repaired an HP-specific problem with STL import. SPR 13.0276Added checking to make sure that during IGES import subfigure instance entities are not made if the subfigure definition entity is bad. SPR 13.0278Gridgen was not properly exporting WIND data for grids containing more than WIND's default number of blocks (64). This has been fixed. SPR 13.0282Fixed a model size related problem with the tetrahedral solver: it would fail if the model was too small. SPR 13.0284Added missing boundary conditions for prism blocks. SPR 13.0288Added WIND support for 2D grids. SPR 13.0312Fixed a problem with the analysis software boundary condition menu that would cause Gridgen to freeze. SPR 13.0314Fixed a memory allocation problem in the tetrahedral solver related to blocks with a relatively high ratio of surface cells to volume cells. SPR 13.0318A problem that would result in core dumps during block splitting has been fixed. SPR 13.0320Copying and mirroring a structured block would result in a few bad Jacobians in the copied block due to a logic error in the Jacobian classification for block corner cells adjacent to a singularity. This has been fixed. SPR 13.0321Fixed a problem that caused the error message "INTERNAL ERROR - This should NEVER happen." to appear when running the unstructured solver on domains on an IBM. SPR 13.0323Repaired a problem in the code used to assemble a multi-block structured grid into a single block for export to FLUENT. SPR 13.0329Fixed a logic error that would prevent database curves from being joined. SPR 13.0331Gridgen now detects and properly handles legitimate triangular faces containing duplicate triangles so that tetrahedral meshes can be made. SPR 13.0335Made the default state of Mouse Warping be off to resolve an inconsistency with the documentation. Also fixed a few instances where the mouse warped regardless of the status of the switch. SPR 13.0337Improved the IGES reader by allowing for trimming curves that are small relative to the node tolerance. SPR 13.0338Removed the automatic update of node tolerance from the grid transformation commands after it was determined that it wasn't required and it sometimes failed. SPR 13.0339Fixed yet another HP-specific problem related to STL import. SPR 13.0342Joining database constrained connectors across the seam in a periodic (i.e., cylindrical) database surface no longer attempts to regenerate the joined connector's shape in terms of the database surface's parametric coordinates. However, joining connectors across the seam of a periodic database surface is still not a recommended practice. SPR 13.0343Several minor problems were fixed related to aborting from block extrusion that made Gridgen think that they block had been created even though it had not. SPR 13.0344Special logic was added to the topology manager for unstructured domains, unstructured blocks, and prism blocks to account for the presence of pole connectors (which is general you should NOT use in an unstructured mesh). SPR 13.0346Corrected errors in the text printed to the Blackboard when examining database entities. SPR 13.0347Enhanced the elliptic solver's floating boundary condition to allow database constrained corners to float. SPR 13.0349Fixed a drawing problem during block creation that would sometimes cause a failure when drawing blocks than can't be created due to bad topology. SPR 13.0352Change the connector Join command so that when candidate connectors are exhausted the user is returned to the Modify menu rather than the main Connector menu. SPR 13.0353Improved the IGES reader by allowing copious data entities to be used in trimming curves. SPR 13.0354Improved the internal routines used to create offset surfaces so that they may be imported from IGES files. SPR 13.0357An error was repaired that failed to enforce the user's "-1" spacing constraint when applied to a break point on a connector's interior. SPR 13.0358Changed the computation of database surface normal vectors to account for degeneracies in the surface (e.g., intervals with zero surface area). This would cause grid folding in the hyperbolic extrusion of database constrained domains. SPR 13.0360Added extra data to STAR-CD 24-file export so that boundary condition names are visible in Prostar. SPR 13.0361Changed the SCRYU/Tetra export from NASTRAN format to the native SCRYU/Tetra format. SPR 13.0362Added 2D support to the FLUENT interface and added checks for pole domains in the ell counting logic. SPR 13.0366The Windows version of Gridgen now releases its license immediately upon exit. SPR 13.0372Splitting database surfaces on Compaq/DEC hardware no longer causes a failure. SPR 13.0373Fixed a bug that "locked" the Redistribute command's Focus radio button on All even when working on only one connector. SPR 13.0380Copying and translating multiple connectors off a database and using the 3D cursor for translation control used to cause a core dump; now it works just fine. SPR 13.0382Disabled database curves were available for picking during database entity creation. This was fixed. SPR 13.0384When the elliptic PDE solver is run on a domain that spans a seam in a periodic database surface (i.e., a cylinder) the code now internally treats the database surface as though it were two by secretly splitting the surface at its parametric midpoint. This prevents the solver from doing very bad things to the grid in the vicinity of the seam due to the large jump in parametric coordinate values at points that are physically adjacent. SPR 13.0386Increased the size of the integer field used to print the Number of Points to the Blackboard in Block Examine to 9 digits. SPR 13.0391Improved the formatting and entity count in the IGES Import Summary printed to the shell window. SPR 13.0392Fixed a problem on Windows machines that allowed the Picked DB Ents button in the solver attributes menu to be picked even though no pickable database entities existed. SPR 13.0393Fixed the export of 2D grid data for Fluent to properly account for the relative orientation of the domains. SPR 13.0395Fixed an error in the application of Maximum Surface Deviation as an unstructured domain point insertion criterion. The grid now more closely follows the user's input value. SPR 13.0396Copies of unstructured domains were being reinitialized in error. This has been fixed. SPR 13.0401Fixed a problem in examining a block's Jacobians that made the Show Cells buttons not work properly. |
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