AcuDdc

Syntax

acuDdc [options]

Type

AcuSolve Solver Program Command

Description

Normally domain decomposition (DDC) is performed automatically by AcuPrep. Advanced users can use AcuDdc to do this step manually. AcuPrep generates the input file needed by AcuDdc. The file name can be found in the .log file and then it is given in the ifile option. It has either a .mts extension, for ASCII files, or a .mts.B extension, for binary files. AcuDdc then writes its output to ofile, which should be the same file name but with a .ddc or .ddc.B extension. This file is read, and the DDC step is bypassed, by -acuPrep when it is restarted:

acuPrep -ddc restart

In the following, the full name of each option is followed by its abbreviated name and its type. For a general description of option specifications, see Command Line Options and Configuration Files. See below for more individual option details:

help or h (boolean)

If set, the program prints a usage message and exits. The usage message includes all available options, their current values and the place where each option is set.

input_file or ifile (string)

Name of the input file. This is a mandatory parameter.

output_file or ofile (string)

Name of the output file. This is a mandatory parameter.

domain_decomposition_technique or ddctech (enumerated)

Domain decomposition technique to be used for decomposing the mesh into subdomains:

metis: Use METIS from University of Minnesota. METIS is based on technology described in the following reference: "A Fast and Highly Quality Multilevel Scheme for Partitioning Irregular Graphs". George Karypis and Vipin Kumar. SIAM Journal on Scientific Computing, Vol. 20, No. 1, pp. 359-392, 1999.

max_ddc_agglomeration or mda (integer)

Agglomerates elements into clusters of size mda prior to domain decomposition. This option may be necessary for extremely large problems.

file_format or fmt (enumerated)

Format of the internal files:

ascii: ASCII files
binary: Binary files

verbose or v (integer)

Set the verbose level for printing information to the screen. Each higher verbose level prints more information. If verbose is set to 0, or less, only warning and error messages are printed. If verbose is set to 1, basic processing information is printed in addition to warning and error messages. This level is recommended. verbose levels greater than 1 provide information useful only for debugging.

Examples

To use AcuDdc to manually create an output file usable by AcuPrep:

acuDdc -ifile ACUSIM.DIR/channel.6.mts -ofile ACUSIM.DIR/channel.6.ddc \
-ddtech metis -mda 0 -fmt binary -v 1

The input and output file names (ifile and ofile) are mandatory parameters. An error will be issued if either one is not given.

The option domain_decomposition_technique is an advanced option and should rarely be changed from its default value.

The parameter file_format determines if the input and output files are saved in ASCII or binary format. The extension .B on the file name parameters is optional. It will be added or removed automatically based on the value of file_format.

If mda is larger than 1, a pre-agglomeration of elements into clusters of size mda is performed prior to domain decomposition. This reduces the DDC memory requirement, but with the potential cost of yielding an inferior decomposition. This option is particularly useful for extremely large problems with over 200 million nodes or elements.