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decompose

decompose automatically splits a Wind-US structured grid system and, optionally, the corresponding flow file, into smaller grid zones to improve the parallel processing efficiency. By default the .mpc file is read to determine the number of processors. Alternatively, the user may specify the number of processors. The default values for decompose are generally sufficient to generate a grid system with a theoretical parallel efficiency of 90% or greater.

decompose is run from the command line, with the following syntax:

    decompose casename [-help] [-nprocs number] [-olap [number]] [-halfcell] [-frgpts [number]] [-minpts number] [-maxpts number] [-nosplit] [-npass number] [-dat datfile] [-grid cgdfile] [-flow cflfile] [-mpc mpcfile]

The only required input is casename, the base name for the Wind-US files for the original grid system. The various command-line options for decompose are described below.

    -help   Display usage information and quit, ignoring any other options.
 
-nprocs number Desired number of processors. If specified, this option overrides the number of processors defined by the .mpc file.
 
-olap [number] Number of planes to overlap between zones; must be ≥ 0. The default value, if number is not specified, is 1.
 
-halfcell Split zones halfway between the original grid points. This is the default behavior, if neither -olap nor -halfcell is specified. If both -olap and -halfcell are specified, the -halfcell splitting is used.
 
-frgpts [number] Number of fringe planes for overlapped zones; must be > 0 and ≤ the number of overlap planes. The default value, if number is not specified, is 1.
 
-minpts number Desired minimum number of points in any direction. The default value is 10.
 
-maxpts number Desired maximum total number of points in a zone. The default value is 999999999.
 
-nosplit Generate the splitting information, but do not actually split. Performs one pass through the splitting procedure.
 
-npass number Number of passes through splitting procedure. The default value is 2.
 
-dat datfile The original Wind-US input data (.dat) file, entered without the extension (e.g., wing, not wing.dat). The default is the name specified for the input parameter casename.
 
-grid cgdfile The original Wind-US grid (.cgd) file, entered without the extension (e.g., wing, not wing.cgd). The default is the name specified for the input parameter casename.
 
-flow cflfile The original Wind-US flow (.cfl) file, entered without the extension (e.g., wing, not wing.cfl). The default is the name specified for the input parameter casename.
 
-mpc mpcfile The original Wind-US multi-processing control (.mpc) file, entered without the extension (e.g., wing, not wing.mpc). The default is the name specified for the input parameter casename.

Some keywords in the .dat file may not be generated correctly for the split grid system. Keywords not yet fully supported include:

Please check the modified .dat file carefully for warning messages.

A .cfl file with a split grid system originally created by decompose may be processed by the recombine utility to convert back to the original grid system.

decompose creates the following files:

      split.cgd   The output grid file
split.cfl The output flow file (if an original flow file exists)
split.dat The modified input data file. Check this file carefully for warning messages.
split.mpc A copy of the original multi-processor control file (if the original exists)
split.map Detailed mapping of the original zone structure to the split structure
splitcgd.inp Input to the cfsplit utility for the grid file. (cfsplit is used internally by decompose.) This file may safely be deleted.
splitcfl.inp Input to the cfsplit utility for the flow file. (cfsplit is used internally by decompose.) This file may safely be deleted.
split.xxx.* Intermediate files used for multiple splits. These files may safely be deleted.
combinecfl.xxx.inp Input to the cfcombine utility, used by recombine to convert a "split" .cfl file back to the original grid system. (cfcombine is used internally by recombine.) These files should not be deleted.


Last updated 26 Aug 2015