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Subset Extraction and Interpolation

This document describes routines to extract a subset from a CGNS data file and interpolate a solution from one CGNS file to another.

Extract Subset extract_subset Extract subset from structured CGNS file.
Interpolation interpolate_cgns Interpolate solution from one CGNS file to another



Extract Subset

Extracts a subset of the grid from a structured CGNS file.

Command Line

The program is executed from the command line as:

extract_subset options CGNSfile newCGNSfile

The input CGNS file, CGNSfile is required. If the output CGNS file, newCGNSfile, is specified the modified CGNS data file will be written to it, otherwise CGNSfile will be modified. The command line options are:

option description
-w use volume weighted averaging (default is simple averaging)
-b base use CGNS base index base. (default 1)
-z zone read zone number zone (default all zones)
-B name write subset to base name (default is same as read)
-i subset in i-direction
-j subset in j-direction
-k subset in k-direction
-a subset in i,j and k-directions (default)

CGNSview Interface

The following panel is created when launched from the CGNSview GUI:

CGNSview Extract Subset window

This allows interactive selection of the input and output files and options. The Accept button will then construct the command line and run extract_subset. If the extraction is successful, CGNSview will read and display the CGNS file.


Interpolation

Reads a solution from one CGNS file and interpolates the solution onto the grid from another CGNS file.

Command Line

The program is executed from the command line as:

interpolate_cgns options CGNSsol CGNSgrid newCGNSfile

The solution CGNS file, CGNSsol, and the grid CGNS file, CGNSgrid, are required. If the output CGNS file, newCGNSfile, is specified the modified CGNS data file will be written to it, otherwise CGNSgrid will be modified. The command line options are:

option description
-c base use CGNS base index base for the solution file. (default 1)
-b base use CGNS base index base for the grid file. (default 1)
-B name write results to base name (default is same as read)
-S name write to solution name (default is same as read)
-w use volume weighted averaging (default is simple averaging)
-a allow element extrapolation
-d depth set max depth for octtree to depth (default 16)
-e nelem set max elements in an octtree branch to nelem (default 256)
-p pad set the bounding box padding fraction to pad (default 0.01)
-i iter set the max number of Newton interations to iter (default 20)
-t tol set the parametric u, v, w tolerance to tol (default 0.00001)

CGNSview Interface

The following panel is created when launched from the CGNSview GUI:

CGNSview Interpolation window

This allows interactive selection of the input and output files and options. The Accept button will then construct the command line and run interpolate_cgns. If the interpolation is successful, CGNSview will read and display the CGNS file.