USS_U²NCLE Toolkit: gridmerge

The "gridmerge" utility allows two or more volume grids to be joined together into one composited grid. Gridmerge resolves the connectivity issues between the constituent grids, such that the final output grid is a valid unstructured mesh.

Note that the output grid has additional data appended to the grid file which gives the "volume tag" of each node in the composite grid. The volume tag is simply equivalent to the grid number as listed from within gridmerge (the output of gridmerge will also list the mapping between the input grid names and the volume tags).

The typical use of gridmerge is to join one or more grids in the context of using the UVI or UBI technique to simulate rotating components. In this setting, the grids should be merged by an Outside-In method; i.e., the outermost grid is given first in the grid list, and a grid within this outermost grid is given second, and so on.

View Example

The command line options recognized by gridmerge are documented below:

-ngrid [#]

Mandatory

The option specifies the number of grids to be composited. Upon execution, the gridmerge utility will prompt for the grid names to be joined.

-ogrid [grid_file_name]

Mandatory

This option specifies the name of the grid file to be output by gridmerge.

-abs_tol

Use absolute tolerancing to find matching nodes between grids instead of local tolerancing. This method is much faster but less reliable.

-rel_tol

Use local tolerancing instead of absolute tolerancing to find matching nodes between grids.

-debug

Prints out extra debugging information useful for developers.

-dumpvtags

This option creates an ASCII file that holds the volume tags for the composited grid.

-help

This option prints a help summary of the usage of gridmerge.

-printrejects

If points are rejected during the merge process, print out information for these nodes.

-renum_tag

Renumber the input surface ID's such that each surface in the constituent grids is mapped to a unique ID number (excepting the surfaces discarded due to the merge). Default behavior is to retain the surface ID's of the constituent grids in the final composited grid.

Output from gridmerge shows the mapping between the old and new surface ID numbers, in any case.

-cat

do not attempt to merge grid points; instead, simply concatenate the grids together.

Output from gridmerge shows the mapping between the old and new surface ID numbers, in any case.

-tolerance [tol]

This option specifies the maximum distance between two points such that they are considered as matching between constituent grids. The default is 1.0e-14.

-flow

Merge solution files in addition to grid files.

-version

Prints the version number of gridmerge.

For further information related to the materials in this web site, USS_U²NCLE, U²NCLE, SolidMesh, DIVA or information related to their use, please contact:

David L. Marcum
marcum@erc.msstate.edu

Phone: (662) 325-3193, FAX: (662) 325-7692

Computational Simulation and Design Center
Engineering Research Center for Computational Field Simulation
Mississippi State University
Box 9627, Mississippi State, MS 39762

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