A: To install everything typically contained on a Gridgen installation CD, including executables, samples, and help files, you will need approximately 100 MBytes of disk space available.

Q: Do I need to be logged in as root to install Gridgen and FLEXlm?

A: If you follow our suggested Installation procedure, you may need to be root to install in "/usr/local". However, any user can install Gridgen and the FLEXlm License Manager. Once a license file has been requested from licenses@pointwise.com, any user can also install the license file and start the FLEXlm license manager daemon.

Q: How can I get Gridgen for Windows if I'm already running on Unix?

A: All Gridgen installation CDs contain software for all the platforms Gridgen supports including Unix, Linux, and Windows.

Q: What kind of hardware do I need to install and run Gridgen?

A: Gridgen's hardware requirements are listed on this page in the Gridgen section of our web site.

Q: Why do I have two sets of documentation pdfs after upgrading to the latest maintenance release?

A: This is due to a structural change in Gridgen's documentation. In the gridgen_home_path/doc directory, there are four new directories which contain the latest pdfs. You will need to delete the old pdf files (gridgen_home_path/doc/userman.pdf, gridgen_home_path/doc/glyph.pdf, gridgen_home_path/doc/tutorial.pdf, and gridgen_home_path/doc/relnotes.pdf) and use the new pdfs in the userman/, glyph/, tutorial/, and relnotes/ directories for reference.

Q: Why can't I get the latest version of Gridgen to run after upgrading from V13?

A: You most likely still have V13 environment variables set, such as GRIDGEN_HOME. If the old environment variables from V13 are present, they can affect Gridgen's ability to function. This is due to the fact that our latest version of Gridgen actually sets up the environment variables it needs at startup and unsets them at shutdown. If you find that you do have these environment variables set, please remove them. You may need to restart your machine once you have removed them.

Q: Why won't Gridgen run now that I've upgraded my Sun Workstation OS to Solaris 9?

A: This problem involves communication issues between FLEXlm and Sun Solaris 9. To fix this issue you will need to add some commands to your normal server startup procedure.

If you use a script to launch the lmgrd daemon (to start the Gridgen server), you will need to add the following two lines to the script preceding the lmgrd command:

ulimit -n 1024
ulimit -H -n 1024

If you launch lmgrd by hand from the command line, we suggest you create a script similar to the simple one below to launch Gridgen:

#!/bin/sh
ulimit -n 1024
ulimit -H -n 1024
lmgrd -c /usr/local/GridgenV15/licenses/gridgen_flexlm.lic 
      -l /usr/local/GridgenV15/licenses/gridgen_flexlm.log

Q: Why doesn't the installation script on my Gridgen installation CD have execute permissions?

A: What you have most likely encountered is the fact that some operating systems will not mount a CD with execute permissions. To successfully run the installation script from the CD on such an operating system, you will need to do the following:

cd mount_directory/gridgen
sh ./install.sh

License Management

How do I determine my Host ID and Host Name?

How do I shut down my license server?

How do I tell my Windows client machine where the license or server is located?

How do I tell my Unix client machine where the license or server is located?

Why doesn't the FLEXlm daemon recognize the new expiration date after I install a new license file?

How do I determine where FLEXlm is looking for a license on Windows?

How do I determine where FLEXlm is looking for a license on UNIX platforms?

How do I determine which ports I need to open for FLEXlm's daemons?

Why does the FLEXlm log file say that I have multiple gridgend servers running?

Will having different hostnames on my Linux/Windows dual-boot system invalidate my license file?

If my system has two ethernet cards, what information is needed to generate a license file?

Why do I get -15 Winsock error: invalid Socket when running Gridgen on Windows with a license served from an SGI?

Which port do I open to allow Gridgen and FLEXlm to communicate through a firewall?

How can I determine which port Gridgen is using on a remote license server?

How can I make FLEXlm automatically start after a reboot?

Why does Gridgen seem to hang on my Windows XP machine unless I frequently resize the window?

Why can't I run three Gridgens simultaneously when I have three FEATURE lines in my license file?

Q: How do I determine my Host ID and Host Name?

A: Instructions for determining your Host ID and Host Name can be found in the Installation Instructions (PDF documents) on our web site for Windows and for Unix and Linux.

Q: How do I shut down my license server?

A: It depends on what platform you are running Gridgen on. If you are running on a Unix/Linux platform, the command lmutil lmdown will shut down the license server. If you are running on a Windows platform, go to Start Menu -> All Programs -> Pointwise -> GridgenV15 -> LMTOOLS. Under the Start/Stop/Reread tab, press Stop Server to shut down the license server.

Q: How do I tell my Windows client machine where the license or server is located?

A: On Windows client machines, the first time you start Gridgen you will see a pop-up dialog box which asks you to specify either the location of the license file or the server. We recommend that you specify the location of the server. There are several ways to specify the server, depending on the setup of your client machine and your network:

@MyServerName (Client machine has an accurate host table)
MyLmgrdPort@MyServerName (Including the port number sometimes necessary for clients with host tables and firewalls)
@MyIPAddress (Client machine has no host table)

Q: How do I tell my Unix client machine where the license or server is located?

A: On Unix, Linux, or Mac client machines, to point the client machine at the server or license, you will need to set the environment variable, GRIDGEND_LICENSE_FILE, equal to one of the following four values:

@MyServerName (Client machine has an accurate host table)
MyLmgrdPort@MyServerName (Including the port number sometimes necessary for clients with host tables and firewalls)
@MyIPAddress (Client machine has no host table)
path_to_the_license_file/gridgen_flexlm.lic

If you do not wish to change this environment variable on the command line, you can edit it in the file .flexlmrc in your home directory.

Q: Why doesn't the FLEXlm daemon recognize the new expiration date after I install a new license file?

A: Execute the following command on Unix/Linux platforms: Lmutil lmreread –vendor gridgend On Windows platforms go to: Start Menu -> All Programs -> Pointwise -> GridgenV15 -> LMTOOLS. Select the Start/Stop/Reread tab, and press "ReRead License File".

Q: How do I determine where FLEXlm is looking for a license on Windows?

A: Run lmtools. Choose the Utilities tab. Click the List All Vendor Paths button. Look for the gridgend line. Use the Append button or Override button to modify the path. (One can also edit the registry entry for

HKEY_LOCAL_MACHINE\SOFTWARE\FLEXlm License Manager\
   GRIDGEND_LICENSE_FILE

but this is not recommended except as a last resort.)

Q: How do I determine where FLEXlm is looking for a license on UNIX platforms?

A: Look at the .flexlmrc file in your home directory using your favorite editor. There will be a line for GRIDGEND_LICENSE_FILE specifying the search path. In the absence of such a file or entry, Gridgen looks in $GRIDGEN_HOME/licenses.

Q: How do I determine which ports I need to open for FLEXlm's daemons?

A: Look at the log file that you specified when starting your FLEXlm server. This file will contain lines near the top of the file detailing which ports the lmgrd and gridgend daemons are using.

Q: Why does the FLEXlm log file say that I have multiple gridgend servers running?

A: There is probably an old lock file left by a previous gridgend process that did not shut down cleanly. Look for a lockgridgend file in the temporary directory used by the user that last launched the license server and remove it. Stop any currently running license managers (lmutil lmdown). You should now be able to start the license manager.

Q: Will having different hostnames on my Linux/Windows dual-boot system invalidate my license file?

A: No. The lmhostid is used to calculate the key, not the server hostname. The lmhostid should be the same for both since it comes from the Ethernet card. Since it is the same, the user should have two copies of his license file. The one for Windows should have the server name set to the Windows server hostname. The Linux license file should have the server hostname associated with the machine when booted under Linux. Another option is to add an alias for the Window's hostname in the /etc/hosts file under Linux.

Q: If my system has two ethernet cards, what information is needed to generate a license file?

A: In FLEXlm, the license files are linked to the Ethernet card address. The number of Ethernet cards in a system does not change the procedure for getting the Host ID and Hostname. Cut and paste whatever Host ID and Hostname the LMTOOLS (Windows) or lmutil (Unix/Linux) utilities display into an email addressed to licenses@pointwise.com. This information and your Customer ID are all that is needed for your key generation.

Q: Why do I get -15 Winsock error: invalid Socket when running Gridgen on Windows with a license served from an SGI?

Q: The most likely cause of this error message is that a firewall exists between the two machines. Configuring the firewall to let Gridgen and FLEXlm communicate through it will take care of the issue.

Q: Which port do I open to allow Gridgen and FLEXlm to communicate through a firewall?

A: FLEXlm by default will actually use the first available of a range of port numbers: 27000-27009. It is also possible to specify which port you want the software to use, either in the default range or otherwise. For more information, see the FLEXlm End Users Guide (Section 2.2 License File Format) at the Macrovision web site: www.macrovision.com/solutions/esd/support/enduser/TOC.htm.

Q: How can I determine which port Gridgen is using on a remote license server?

A: When the server is started up, it lists the port in the log. The log can generally found in the same location as the license key. The port listed is typically tcp-27000.

Q: How can I make FLEXlm automatically start after a reboot?

A: This is explained in the FLEXLM documentation at www.macrovision.com/solutions/esd/support/enduser/TOC.htm in Chapter 6., "The License Manager Daemon".

Q: Why does Gridgen seem to hang on my Windows XP machine unless I frequently resize the window?

A: This is a problem with XP related to the conversion of a hostname into an IP address. A work around is to use the IP address instead of the hostname in your license file and by including a Unix-style hosts file in system32\drivers\etc.

Q: Why can't I run three Gridgens simultaneously when I have three FEATURE lines in my license file?

A: You probably have three FEATURE lines because each of the Gridgen processes has a different expiration date. The proper way to do this is to use a FEATURE line for the first license and INCREMENT lines for every license after the first.

Q: How do I determine my Host ID and Host Name?

A: Instructions for determining your Host ID and Host Name can be found in the Installation Instructions (PDF documents) on our web site for Windows and for Unix and Linux.

User Interface

How do I make a picture of my grid?

How can I change the center of rotation for model manipulations?

How can I make Gridgen highlight the entity I wish to pick?

Can I switch the operation of the mouse buttons when using Gridgen?

How can I make the text on grayed-out buttons more legible?

Why do I get the error message "ERROR: Could not create GL format, ERROR: can not set pixel formats, ERROR: startup script failed" when I try to start Gridgen on my PC?

Why can't I see my cross cursor when I am creating a connector? Why won't the connectors highlight when I pick them?

Why does the Display flicker on my SGI when I am rotating or moving my model?

How do I get the Gridgen window to size correctly for one of my machine's multiple displays?

Why is the zoom box so slow even though I have a very high-end graphics card on Linux?

Q: How do I make a picture of my grid?

A: An image file of the Display window can be written by using the buttons labeled Photo in the DISPLAY COMMANDS menu: .bmp to write a bitmap file, .png to write a Portable Network Graphics image file, and .ps to write a PostScript file.

Q: How can I change the center of rotation for model manipulations?

A: Simply hold down the Control key (Ctrl) key on the keyboard while picking any pickable point in the model, including connector nodes, database surface corners, and grid intersections.

Q: How can I make Gridgen highlight the entity I wish to pick?

A: If there is more than one pick candidate entity underneath the cursor, simply use the x hot key on the key board to have Gridgen cycle through the candidates one at a time.

Q: Can I switch the operation of the mouse buttons when using Gridgen?

A: Yes, use the Mous LeftPk toggle in the DISPLAY COMMANDS menu.

Q: How can I make the text on grayed-out buttons more legible?

A: On some Unix machines, the color contrast between the text and button colors on a grayed-out button is very low. For machines running the Common Desktop Environment (CDE) you can fix this by

Select the style manager (on CDE bar).
Select Color.
Select a different palette or edit colors manually.

Q: Why do I get the error message "ERROR: Could not create GL format, ERROR: can not set pixel formats, ERROR: startup script failed" when I try to start Gridgen on my PC?

A: You most likely have your Desktop Settings in 256 color mode. On PC's, Gridgen operates best in either 16-bit or 32-bit color mode.

Q: Why can't I see my cross cursor when I am creating a connector? Why won't the connectors highlight when I pick them?

A: This problem is typically caused by the way your graphics card handles overlays (Gridgen uses overlays by default on some platforms). To resolve the problem, first make sure that your graphics card has the most up-to-date drivers available. Next, you need to change Gridgen's graphics mode to a non-overlay mode. To change the graphics mode, start Gridgen and go to the Display Commands menu. Press Wndw: FramBuf to go to the Reconfigure Graphics menu, where you should select RGB Mode. Once you have done this and verified that it resolved the issue, you may want to save this setting in your gridgenrc file

Q: Why does the Display flicker on my SGI when I am rotating or moving my model?

A: You most likely have your frame buffer mode set to RGB Mode w/ Overlay. Unfortunately, SGI machines only have single buffered overlays. That means that anything drawn in the overlays will flicker as it is moved. To resolve the problem, first make sure that your graphics card has the most up-to-date drivers available. Next, you need to change Gridgen's graphics mode to a non-overlay mode in your gridgenrc file, which can typically be found in your working directory. Once you have found the file, open it in your favorite text editor and add the following line in the DISPLAY section:

gg::dispFrameBuffer CI_12

If this line already exists and is set to some other value, you can simply edit it to use the above value. This command will set the frame buffer mode to a 12-bit Color Index Mode which simulates the double buffered overlays you need.

Q: How do I get the Gridgen window to size correctly for one of my machine's multiple displays?

A: To modify the Gridgen window to fit correctly on one of multiple displays, you will need to add the following to your .gridgenrc (Unix/Linux) or _gridgenrc (Windows) file:

set width 1024
set height 768
gg::tune _MAX_SIZE [list $width $height]

Note: Once added, the values for width and height may have to be changed slightly for a single display.

Q: Why is the zoom box so slow even though I have a very high-end graphics card on Linux?

A: You need to enable color index overlays for Linux distributions using NVidia graphics cards by adding the follow two options to the Device section of the XF86Config file (typically found in /etc/X11):

Option "Overlay" "1"
Option "CIOverlay" 1"

Input/Output

How do I get my structured grid out of Gridgen into my own solver?

How do I get my unstructured grid out of Gridgen into my own solver?

Can I import a structured mesh into Gridgen from another source?

Can I import a unstructured mesh into Gridgen from another source?

Why do I get error messages when importing a STEP file?

Why can't I write a file called CON.gg?

Q: How do I get my structured grid out of Gridgen into my own solver?

A: Use the Generic flow solver setting which will produce a Plot3D formatted grid file and an ascii boundary condition file. Or the new CGNS-Struct flow solver setting can be used to export data formatted according to the CGNS standard. Use Export Analysis Data to have Gridgen write out the files. See Chapters 4 and 30 in the User Manual for more information.

Q: How do I get my unstructured grid out of Gridgen into my own solver?

A: Use the Generic flow solver setting which will produce an FVUNS (FIELDVIEW Unstructured) formatted file. This file also includes boundary condition information. Or the new CGNS-Unstr flow solver setting can be used to export data formatted according to the CGNS standard. Use Export Analysis Data to have Gridgen write out the files. See Chapters 4 and 30 in the User Manual for more information.

Q: Can I import a structured mesh into Gridgen from another source?

A: Yes. The easiest method would be to import the mesh in Plot3D format using the Grid Pts Import command. This approach will work for domains (surface grids) or blocks (volume grids). See Chapters 4 and 30 in the User Manual for more information.

Q: Can I import a unstructured mesh into Gridgen from another source?

A: Yes. The easiest method for blocks (volume grids) would be to import via the FVUNS format using the Grid Pts Import command. For domains (surface grids) you could use the STL or VRML formats using the same command. See Chapters 4 and 30 in the User Manual for more information.

Q: Why do I get error messages when importing a STEP file?

A: Sometimes during STEP file import there will be error messages like Error in acisImportFile: can't import step file and Error 88005 - no entities were read. One of two things usually causes this error message. For STEP file import, it is very important that the Gridgen executable and the step/ sub-directory exist in the same folder and that the user has write permissions in the step/ sub-directory. If both of these are true and the error message still appears, please contact us.

Q: Why can't I write a file called CON.gg?

A: This happens on Windows because CON is reserved for a device filename. Other file names you can't use on Windows are PRN and NUL.

Database

Why do I lose parts of my dimensionally small CAD model when I import an IGES file?

Can I combine database entities from different file types, like IGES and networks?

What happened to database entities that appear to be missing after I import a database file?

Q: Why do I lose parts of my dimensionally small CAD model when I import an IGES file?

A: Gridgen computes tolerances for many database operations from the Model Size set in the Tolerances menu. The default Model Size is 1000. The Model Size should be set to approximately the maximum dimension of your CAD model. For instance, if the model is 9.5 units long, set the Model Size to 10. If you read in a model that is orders of magnitude smaller than the Model Size, then Gridgen may have trouble preserving some of the database entities. For this reason, you should set the Model Size to a smaller value before reading a particularly small CAD model.

Q: Can I combine database entities from different file types, like IGES and networks?

A: Yes, you can import all types of database data into the same session of Gridgen and this data can all be exported together to a single composite database file (.dba).

Q: What happened to database entities that appear to be missing after I import a database file?

A: If no errors were reported during import of the model, more than likely the missing entities are disabled or in a layer that is currently turned off.

Connectors

How can I change multiple spacing constraints at once?

Why does my connector have a General distribution function and is that OK?

Can I change the direction of a connector?

Are there types of connectors that I should avoid?

Q: How can I change multiple spacing constraints at once?

A: You can use the Set Ds Vals command in the Connector Commands menu. This command allows the user to pick any number of break point spacing constraints that should have the same value and specify them all at once. This process can be repeated as necessary from within the command.

Q: Why does my connector have a General distribution function and is that OK?

A: The distribution of grid points on a connector is controlled by a hyperbolic tangent function by default. If you transform or modify the connector's shape in any way or if a connector is created impliclity by a higher-order function (for example, extrusion), Gridgen creates a distribution function that exactly matches the grid points. This is called a general distribution function and is not a bad thing. However, there may be instances where you want to redistribute points and have them behave according to the hyperbolic tangent. In this case you can use the ReDistribute command in Connector, Modify to change the distribution function from General to TANH (you can also do this using Set Delta S Values).

Q: Can I change the direction of a connector?

A: No, it is not possible to change the default orientation of a connector. Connector direction is based on the order you store its control points. The first control point save will always be the beginning of the connector.

Q: Are there types of connectors that I should avoid?

A: Yes. You should not create a connector that begins and ends at the same node (i.e. loops back on itself).

Domains

Why does a connector used in two domains appears to have two different grid point distributions after merging?

Why are some domains green and some purple?

Are there types of domains that I should not create?

Q: Why does a connector used in two domains appears to have two different grid point distributions after merging?

A: This mis-match is due to not having used the Update command after merging the common boundary connectors. An update has to occur to clear up the mis-match. In the Connector menu, in the Merge area, there is a button labeled Update. Pressing this button after merging the connectors shared by the adjacent domains should solve the problem. Using On DB Entities with Auto Merge when creating adjacent domains is a good way to ensure that updates occur automatically.

Q: Why are some domains green and some purple?

A: A newly created domain that is rendered in purple has been initialized so that it conforms to the database. A green domain has not been initialized on the database. Note that these colors are only set when the domain is initially created so that if you later project a domain onto the database its color will not automatically be updated to purple.

Q: Are there types of domains that I should not create?

A: Yes. Here are a few types of domains to avoid.

Don't make two domains that share the same set of connectors. For example, consider a square pillow. The four edges around the pillow are identical but yet define the perimeters of both the upper and lower surfaces. Instead, create the upper and lower surfaces as two domains each.
Don't make two domains that overlap in 3D space. For example, consider a surface with a hole in it. You shouldn't create one domain for the entire surface and then a second domain for the hole that lies on top of the first. Instead, create a domain or series of domains on the surface around the hole. This is true whether or not the edges of the hole share any connectors with the surface.
Don't create a domain that is partially singular. It'll work better if the singular portion of the domain (a surface collapsed to a line) is a domain unto itself.

Blocks

Why aren't interblock connections set correctly after importing a grid from a PLOT3D file?

Why can't I add a triangular structured domain (with a pole at one end) when creating an unstructured block face?

When I'm setting BCs, why isn't there a connection between two adjacent blocks?

Q: Why aren't interblock connections set correctly after importing a grid from a PLOT3D file?

A: Gridgen is unable to automatically match some interfaces where a single block face matches up with multiple other block faces. In these instances the user will end up with overlapping or coincident domains at these interfaces. You must split the larger domains to match the smaller ones. Once splitting is complete, Gridgen will recognize automatically that there are now duplicate coincident domains, remove one of each pair, and set up the interface properly.

Q: Why can't I add a triangular structured domain (with a pole at one end) when creating an unstructured block face?

A: Structured domains with a singular edge are not currently supported for unstructured block face creation.

Q: When I'm setting BCs, why isn't there a connection between two adjacent blocks?

A: The most likely answer is that your blocks have been created in such a way that there are two domains in the interface area. Merging the connectors that make up these domains should merge them into one domain marked as a Type-1 interface.

Structured Solvers

What is a foreground control function?

What is a background control function?

Q: What is a foreground control function?

A: This is a hybrid function of the elliptic PDE solver which enforces spacing and angle constraints to each of the boundaries of a structured grid: the four edges of a domain and the six faces of a block.

Q: What is a background control function?

A: This is a hybrid function of the elliptic PDE solver which enforces smoothing and clustering throughout the interior of a structured grid.

Unstructured Solvers

Why did my unstructured domain move off the database when I reinitialized it?

Why do I get an error message about the GRIDGEN_TEMPDIR directory when I try to initialize my unstructured block?

Q: Why did my unstructured domain move off the database when I reinitialized it?

A: An unstructured domain will move off the database when reinitialized if it had originally been projected onto multiple database entities. The reinitialization process looks only at the boundary points and may not see database entities to which the interior of the domain should be projected.

Q: Why do I get an error message about the GRIDGEN_TEMPDIR directory when I try to initialize my unstructured block?

A: When the unstructured solver is running, it needs a directory space to which it can write temporary files. If this GRIDGEN_TEMPDIR variable is not set (which is generally the case) these temporary files are written to a system-standard temporary directory. If a user does not have write permissions to that directory, Gridgen will not be able to write out these files and will stop the solver with an error message about the GRIDGEN_TEMPDIR not being set. The solution to this situation is to create a new environment variable on your workstation and set it equal to a directory which has free disk space. It is important to remember that the larger your unstructured block, the more disk space you will need to have available in this directory.

Extrusion

In the Extrusion section, what does the Aspect Ratio Factor in the Set Attributes Menu do?

How may I extrude several domains at once if they don't form a single face?

Can I extrude structured and unstructured domains simultaneously into blocks?

Why do I keep getting axis error messages when I try to rotationally extrude my unstructured domain?

Q: In the Extrusion section, what does the Aspect Ratio Factor in the Set Attributes Menu do?

A: The aspect ratio factor makes an adjustment to the local marching step size based on the size of the local cell. At each step, the smallest cell will receive the input physical step size. All other cells will receive a larger step size based on their size compared to the smallest cell and the value of the aspect ratio factor.

delta S = (size local) / (size min) * specified delta S * AR factor

Q: How may I extrude several domains at once if they don't form a single face?

A: You should use Block, Create, Extrude from Doms. You select all the domains to be extruded and one block will be created for each structured domain selected. If the domains are adjacent and share connectors, the extruded blocks will also be connected along that common boundary.

Q: Can I extrude structured and unstructured domains simultaneously into blocks?

A: Yes. Structured and unstructured domains can be extruded together into blocks by using Block, Create, Extrude from Doms. This command will allow you to select both types of domains from the Browser window, after which you will need to specify extrusion attributes for the various domains.

Q: Why do I keep getting axis error messages when I try to rotationally extrude my unstructured domain?

A: Gridgen will not allow the rotation axis to lie on an edge of your unstructured domain such that prisms with degenerate faces would result from a rotational extrusion. Prisms with degenerate faces are not currently supported. It is OK if the axis is displaced from the unstructured domain such that normal prisms will be created from the extrusion. Otherwise, a single cell wide structured domain can be created between your unstructured domain and the axis for the rotational extrusion.

Miscellaneous

How can I estimate Gridgen's memory usage?

Why does Gridgen never use more than 2 Gb of memory even though I have much more?

What is the IP address of Pointwise's ftp server?

How can I specify which browser Gridgen will use for its on-line help?

How can I specify a start-in directory different from gridgen_home_path/My Grids on my PC?

How do I tell Gridgen to execute a script file everytime it starts?

Q: How can I estimate Gridgen's memory usage?

A: The different solver formats that can be chosen for exporting your grid each have their own memory requirements. To be safe, we will try to give you an idea of the memory requirements for FLUENT, which has some of the highest demands. For Fluent, export is face based. Each cell face requires 28 bytes of memory. So to estimate memory requirements in bytes, the formula is as follows:

num_cells*num_faces_per_cell*28

where the number of faces per cell is 4, 5, 6 for tet, prism, and hex, respectively.

In an all tetrahedral grid, the number of points to cells is roughly 1:6. Whereas for a structured grid, the point to cell ratio is usually around 1:1. So if the 10 million point grid you have is all tetrahedra, it would be roughly 60M cells. If the grid is all hexahedra, it would be roughly 10M cells.

To convert to MB, remember that in the computer memory world 1 MB = 1,048,576 bytes. The memory estimate formula above does not include a much smaller amount of required memory for points, BC's, etc.

So if your case is all tets, the rough memory requirements would be:

(60,000,000)(4)(28)/1,048,576 = 6,409MB = 6.26GB

If your case is all hexahedra, the memory requirements would be:

(10,000,000)(6)(28)/1,048,576 = 1602MB = 1.6GB

In general, an all tetrahedral grid version of a grid will require the most memory.

Remember that in its current 32-bit form, Gridgen can access at most 2GB of RAM. WinXP has its own built-in process limit that appears to be about 1600 MB. Our 64-bit releases of Pointwise will be able to surpass the 2 GB limit natively.

Q: Why does Gridgen never use more than 2 Gb of memory even though I have much more?

A: Since Gridgen is compiled 32-bit, it can only address up to 2 Gb of memory. However, you may see a lower artificial limit on either the HP or IBM platforms due to the system's default datasize limit. This limit can be adjusted by the user on IBM platforms, but must be changed with a kernel rebuild by the system administrator on HP platforms.

Q: What is the IP address of Pointwise's ftp server?

A: The IP address of Pointwise's ftp server is ftp.pointwise.com.

Q: How can I specify which browser Gridgen will use for its on-line help?

A: On Unix systems, you can specify the browser Gridgen will use for its on-line help by setting the environment variable GRIDGEN_NETSCAPE_EXE to the complete pathname of the browser's executable file.

Q: How can I specify a start-in directory different from gridgen_home_path/My Grids on my PC?

A: The My Grids folder is created and set as your start-in directory during Gridgen installation. When browsing for files or saving files in Gridgen, My Grids is the first directory Gridgen pulls up. To have Gridgen use a different start-in directory, right-click on the Gridgen icon on your desktop and choose Properties. Under the Shortcut tab, change the directory path in the Start-In: field to one of your choosing, then press Apply and OK.

Q: How do I tell Gridgen to execute a script file everytime it starts?

A: A script file that is executed automatically everytime that Gridgen starts is called an "RC" file and it is just a regular Glyph script. There are several places that Gridgen looks for an RC file.

First, it looks to see whether the GRIDGEN_RCFILE environment variable is set (note: this environment variable is deprecated and may not be supported in future releases).
If GRIDGEN_RCFILE is not set, Gridgen looks for a file called _gridgenrc (.gridgenrc on Unix) in the starting directory.
If there's no RC file there, Gridgen looks for _gridgenrc (.gridgenrc on Unix) in the user's home directory.

To determine your home directory on Win32, Gridgen looks for the environment variables HOMEDRIVE and HOMEPATH. If HOMEDRIVE does not exist, it looks for HOME. You can examine the value of these environment values by typing "set HOME" at a DOS prompt. If they exist, you should combine HOMEDRIVE and HOMEPATH to get the home directory.

Diagnostics

How can I make small cells more visible in Examine?

Is there an easy way to visualize the quality of viscous orthogonality and spacing in my structured grid?

Q: How can I make small cells more visible in Examine?

A: If you set the Shrink Factor to zero (in the Examine command's Display Style menu), the cells are drawn using filled circles that have a constant size so that small cells are readily visible.

Q: Is there an easy way to visualize the quality of viscous orthogonality and spacing in my structured grid?

A: Yes, proceed to the ANALYSIS S/W COMMANDS menu, select Examine, choose the block face domains in question (viscous surfaces), and use the Function None command to select either spacing or orthogonality.

Analysis Software Interfaces

Why is the Export Analysis Data button grayed out?

Can I set Physical Constants for my solver in Gridgen?

Why won't the WIND .cgd file from V14 import into GMAN?

Why doesn't Gridgen recognize my interblock connections when I'm setting BCs?

Why can't I set BCs on my 2D grid?

How do I create periodic boundaries?

Q: Why is the Export Analysis Data button grayed out?

A: For an unstructured mesh, you need to create a volume grid before you export the ASW data. That is, initialize your block via "Block Commands, Run Solver Unstrctrd".

Q: Can I set Physical Constants for my solver in Gridgen?

A: Gridgen is unable to set physical values like pressures and temperatures for your flow solver. If this type of data is required in the boundary condition file, you must edit the file and add the additional parameters.

Q: Why won't my WIND .cgd file exported from V14 import into GMAN?

A: Gridgen V14 uses ADF Library Version A02011. The Win32 version of GMAN is based on an older version of this library. Because of this library mismatch, the .cgd files exported by V14 can't be imported by GMAN.

Q: Why doesn't Gridgen recognize my interblock connections when I'm setting BCs?

A: Gridgen only automatically recognizes point-to-point (Type I) connectivity. If your interblock connections use arbitrary matching you should create a custom boundary condition.

Q: Why can't I set BCs on my 2D grid?

A: Because Gridgen can only set boundary conditions on blocks, you probably haven't yet created 2D blocks from your domains. Even if your grid is 2D you need to create 2D blocks. There are benefits to doing this - you can combine several domains into a single block and you can explicitly control the orientation of the computational axes of a structured block.

Q: How do I create periodic boundaries?

A: In the Connector and/or Domain menus the commands Periodic Trans and Periodic Rotate should be used to create pairs of period grid entities. Gridgen will then automatically assign a periodic flow solver BC (in the same way that it automatically creates interblock connections.)

Glyph Scripting

How can I make file i/o in my script independent of the directory?

Can I run Gridgen in batch without the GUI?

Where can I find out more about the Tcl/Tk programming language?

Q: How can I make file i/o in my script independent of the directory?

A: Use the following Tcl commands to base your file i/o on the current directory.

# get directory from which script was run
set scriptDir [file dirname [info script]]
# set the file name
set fileName "myfile.gg"
# import the file
gg::gridImport [file join $scriptDir $fileName]

Q: Can I run Gridgen in batch without the GUI?

A: Yes, just provide the "-b" command line argument after the executable on the command line and prior to your Glyph script filename. For example, "gridgen -b myscript.glf". Note however, that even when running in batch, the Gridgen executable needs to be run on a system with OpenGL installed.

Q: Where can I find out more about the Tcl/Tk programming language?

A: Please go to the following web page for more information: http://www.tcl.tk/