Gridgen - Pointwise's Legacy Meshing Software

Gridgen is Pointwise's legacy software, used by engineers and scientists worldwide to reliably generate high quality grids for CFD. Development began in 1984 and the software was retired in 2016.

Flexible CAD Interoperability

Interoperability of computer aided design (CAD) models (or the lack thereof) poses significant challenges to the CFD practitioner. Other meshing software forces analysts to interface directly with the CAD system, tying up a valuable software asset and requiring significant software training. Gridgen provides a flexible suite of CAD data access methods, allowing the analyst to select the optimum approach.

Solid Meshing Recovers Engineering Topology

One approach to working with complex geometry models in Gridgen is Solid Meshing. This technique involves recovering the "engineering topology" from the rather arbitrary CAD topology. The engineering topology reduces a geometry model to major components relevant to meshing like wings, blades, and sidewalls. This is accomplished using tools that provide solid model import and creation.

Once a solid model of the geometry has been created, all the seams between adjacent surfaces are closed and meshing can proceed without having to deal with special issues related to gaps and overlaps.

Read more about how solid modeling simplifies the geometry and makes it easier to mesh.

Fault-Tolerant Meshing Eliminates CAD Healing

Another problem with CAD model interoperability is sloppy geometry such as gaps between adjacent surfaces, overlapping surfaces, and missing features. An analyst must be able to mesh a less than perfect model. Even though other software attempts to "heal" the CAD model through a variety of manipulations, healing is an ill-defined problem since design intent is usually unknown. Using a technique called Fault Tolerant Meshing, Gridgen is able to create a fully closed mesh on a sloppy CAD model. Merging automatically identifies adjacent surface meshes, joins them across CAD model gaps, and uses the mesh solver to remove CAD artifacts such as topology and sliver surfaces from the mesh.

Geometry Modeling

Gridgen does not require the use of a CAD model for meshing - the mesh can be created directly in 3D without having to create geometry first. This feature lessens dependence on the CAD system, allowing the analyst to use CAD geometry only where necessary. Furthermore, Gridgen's geometry modeler may be used to supplement the CAD model and create new models from scratch:

• points and lines
• Catmull-Rom and Akima splines,
• offsets, conics, circles,
• intersections,
• ruled, revolution, linear sweep, polyconic, coons, and fit surfaces
• trimmed surfaces

Also, Gridgen's hybrid geometry kernel allows models to be imported in de facto standard formats such as PLOT3D wireframes and STL triangular faceted data.

When meshing complex CAD models, Gridgen can create meshes that are independent of the CAD topology. A mesh may span an entire CAD surface, only a portion of a surface, or multiple surfaces.

Read more about how Gridgen ensures your geometry is analysis ready whether it is analytic or faceted.

Direct CAD Access

Through a partnership with CADNexus, a direct method for obtaining CAD data without translation is available for Gridgen users. CAPRI2NMB is a CAPRI CAE Gateway application that works directly with a CAD system's native kernel. Gridgen's native NMB geometry file is produced automatically by direct queries into the CAD model. The NMB file is then simply imported into Gridgen. Because CAPRI2NMB works directly with the CAD software, it has the potential to provide more robust geometry transfer. CADNexus supports CATIA V5, Pro/E, UG NX, SolidsWorks, Parasolid, and OpenCASCADE.

Structured Hex Grids

Structured grids containing mapped hexahedra or quadrilaterals are initialized using transfinite interpolation (TFI) algebraic techniques and adhere automatically to the CAD model wherever possible using standard, linear, polar, and orthogonal TFI, and parametric and parametric fit TFI.

The quality of structured grids can be significantly improved by applying Gridgen's elliptic PDE methods. These methods iteratively solve Poisson's equation. While the defaults have been set to provide the nominal grid, the control functions can be fine tuned at any time using the following techniques:

• Laplace (smoothness)
• Thomas-Middlecoff (clustering)
• Fixed Grid (smoothness)
• von Lavante-Hilgenstock-White, and Steger-Sorenson (orthogonality).

Structured grids with high degrees of orthogonality and clustering control can also be created using Gridgen's hyperbolic PDE and algebraic extrusion methods. All of the extrusion methods can be applied to 2D grids, surface grids constrained to CAD surfaces, and volume grids. The hyperbolic method is especially well suited for CFD solvers that use overlapping grids but contains features to extrude multi-block abutting grids as well.

Overset Grid Assembly Integration

Gridgen interfaces directly with overset grid assembly (OGA) software packages PEGASUS5 and SUGGAR including customized interfaces for hole-cutting setup and launch. The OGA results are imported as IBLANK data including fringe, hole, and orphan objects. You can then control the display of all these objects throughout the gridding process in order to ensure that your overset grid will result in an accurate CFD solution.

Unstructured & Hybrid Meshes

Unstructured and hybrid mesh generation offer fast, highly automated methods for generating a CFD mesh. Gridgen provides several methods from which you can choose the one most appropriate to your analysis.

Anisotropic Tetrahedral Extrusion

Anisotropic tetrahedral extrusion, otherwise known as T-Rex, is a technique for extruding regular layers of high-quality tetrahedra from boundaries. The tetrahedra can be recombined into prisms if you prefer. The mesh adjusts to convex and concave regions and colliding extrusion fronts.

An optional post-processing step combines a stack of three anisotropic tetrahedra into a single prism, reducing cell count and providing an even higher quality cell in the near-wall region.

Read about how T-Rex generates high quality meshes that lead to accurate CFD solutions.

Direct Prism Extrusion

Prism layers are created by the extrusion of triangular surface grids following normal, linear, rotational, or user-defined paths with control over extrusion step size or aspect ratio.

Tet Generation with Delaunay Methods

Unstructured grids consisting of triangles and tetrahedra are generated by a modified Delaunay method. Like structured grids, unstructured surface grids can span multiple entities in the geometry model and adhere to the CAD model automatically. The unstructured solver may be re-applied at any time, giving you control over minimum and maximum cell size, maximum cell-to-cell turning angle, maximum surface deviation, and boundary decay.

These attributes may also be set in advance to result in a good grid automatically. Edge swapping and Laplace smoothing may also further improve unstructured surface grids.

Automate & Customize Meshing

Gridgen's Tcl-based scripting language, Glyph, provides customization capabilities for both the experienced analyst and the "design engineer". The experienced analyst will find that Glyph's commands cover the entire range of functionality available in Gridgen's GUI, allowing tricks and special techniques to be captured and made part of the organization's intellectual property. Designing engineers will appreciate the fact that Glyph may be used to create customized meshing applications for specific configurations, allowing them to automatically generate a mesh and apply CFD.

Journal Your Session for Editing Playback

Glyph scripting is complemented with a journaling capability. Gridgen exports the Glyph form of each GUI command to a file for later editing and playback. Journaling is further complemented with variables, name-value pairs that may be defined and utilized in the GUI so that a journaled Glyph script can be easily edited for parametric variation of a baseline mesh.

Read more about Gridgen's Glyph scripting in this article.

Supported Platforms

Using the industry-standard OpenGL^® graphics API, Gridgen's interactivity and 3D graphics are available on a variety of Windows^® (Intel^® and AMD^®), Linux^® (Intel^® and AMD^®), Mac^®, and Unix^® (SGI^®, HP^®, and Sun^®), workstations, all with the same look and feel and transportable Gridgen native file. Gridgen's graphical user interface (GUI) guides engineers through preprocessing, eliminates extraneous menus, and uses a consistent menu system and nomenclature for the entire process, from CAD model import/creation through volume grid generation and analysis software file export. When combined these features make Gridgen easy to learn, easy to use, and easy to remember how to use.

	Hardware	32-bit	64-bit	Details
Microsoft Windows	Intel AMD
Linux	Intel AMD
Mac OS X	Intel
SGI IRIX	MIPS
HP HP-UX	PA-RISC
Sun Solaris	SPARC

Other features of the GUI are:

• mouse or keyboard operation
• "mode-less" image pan, zoom, and rotate
• PostScript^®, PNG, BMP and SGI RGB output
• HTML-based on-line, context-sensitive help
• Heterogeneous license management, allowing "license once, run anywhere"
• Common GUI and Gridgen native files across all platforms

All Platforms

Minimum Requirements:

• 128 Mbytes RAM
• 100 Mbytes disk space
• OpenGL capable color display
• Ethernet card
• CD-ROM drive

Recommended Requirements:

• 3D hardware accelerated OpenGL graphics
• double-buffered overlay planes or 24-bit RGB double buffered graphics

Windows

Gridgen supports Windows on both AMD and Intel.

• Intel IA-32 Architecture
• Microsoft Windows 7, Windows Vista and Windows XP (Gridgen may operate properly on Windows 95, 98, NT, ME, and 2000 but this operation is unsupported.)
• at least 1024x768 resolution in High Color (16 bit) Display Mode
• Compatible Graphics Accelerators*
• NVIDIA GeForce and Quadro
• ATI Rage
• ATI Radeon
• Graphics Accelerators with Known Problems
• NVIDIA Quadro FX4600 - The NVIDIA-Linux-x86_64-180.22-pkg2.run driver and RedHat 5.3 have incompatibilities which cause significant issues with Gridgen's display. Older NVIDIA drivers do not exhibit this problem.

Linux

Gridgen supports Linux on both AMD and Intel for both 32-bit and 64-bit.

Linux installations must include:

• libstdc++ libraries
• glibc v2.3.4 libraries
• GNU c++ runtime libraries (v3.4.6+)
• X11R6.8.2 (X.Org or XFree86)
• OpenGL 1.4

Under RedHat Enterprise Linux 5 (32 and 64 bit) the specific libraries and the package from which they may be installed are listed below. (For other Linux distributions, we recommend using rpmfind.net to determine which packages to install.):

A recommended minimum platform configuration is:

• RedHat Enterprise Linux 5 with version 1.0-9631 of the NVidia X.Org binary drivers for NVidia-based graphics cards

To configure overlays and other graphics options for your graphics card, please refer to your card vendor's documentation.

Gridgen may run on Linux platforms other than the one recommended above if the required libraries are installed. For users of OpenSuse 10.2 and 10.3, the additional package, compat-f77, may be necessary for Gridgen to run properly.

Mac

• Apple Mac workstations
• Only Intel-based Macs are supported.
• Mac OS X V10.4 and higher
• X11
• NVidia GeForce Graphics Accelerator

Hewlett-Packard

• HP-UX 11.11 on PA-RISC
• Visualize b-, c-, and j-class Unix Workstations
  Series 700 Workstations
• Visualize fx2, fx4, fx5, fx6, fx10 Graphics

SGI

• Prism, Fuel, Onyx2, Onyx, Octane2, Octane, O2, Indigo2, Indy
• IRIX 6.5
• All Graphics

Sun

• UltraSPARC Workstations
• Solaris 8
• Creator3D, Elite3D, and Expert3D Graphics Accelerators

*Up-to-date graphic accelerator driver software is essential for proper operation of Gridgen.

CFD Solver Interfaces

Gridgen supports neutral, native, and de facto standard interfaces to CFD solvers (including the specification of solver boundary conditions), grid files, and geometry formats to ensure that Gridgen fits into your CFD process.

Grid and Flow Solver Data Export

Grids and flow solver data (e.g. boundary conditions) can be exported from Gridgen to the following formats.

Grid Import and Export

Just the grids themselves can be imported and exported to and from a variety of formats.

Geometry Import and Export

Geometry on which the grid will be generated (database in Gridgen's vernacular) can be imported from and exported to a variety of formats.

Read more about Gridgen's interoperability in this article.

Try Pointwise

Now that Gridgen has been retired, it's time to start using Pointwise.

Better, faster meshes start with a free trial. Request one today and begin putting Pointwise to use.