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write_surf command


write_surf file 


write_surf type custom temperature custom flags
write_surf points no
write_surf nfile 50 


Write a surface file in text format describing the currently defined surface elements, whether they be explicit or implicit surfaces. See the read_surf and read_isurf commands for a definition of surface elements and how they are defined and used be SPARTA. The surface file can be used for later input to a new simulation or for post-processing and visualization.

Note that if surface objects were clipped when read in by the read_surf command then some surface elements may have been deleted and new ones created. Likewise for the points that define the end points or corner points of surface element lines (2d) or triangles (3d). Similarly, if surface elements have been removed by the remove_surf command, then points may have also been deleted. In either case, surface points and elements are renumbered by these operations to create compressed, contiguous lists. These lists are what is output by this command.

The output file is written as a text file in the same format as the file the read_surf command reads for explicit surfaces.

Similar to dump files, the surface filename can contain two wild-card characters. If a "*" appears in the filename, it is replaced with the current timestep value. If a "%" character appears in the filename, then one file is written by each processor and the "%" character is replaced with the processor ID from 0 to P-1. An additional file with the "%" replaced by "base" is also written, which contains global information, i.e. just the header information for the number of points and lines or triangles, as described on the read_surf doc page.

For example, the files written for filename data.% would be data.base, data.0, data.1, ..., data.P-1. This creates smaller files and can be a fast mode of output and subsequent input on parallel machines that support parallel I/O. The optional fileper and nfile keywords discussed below can alter the number of files written.

Note that implicit surfaces read in by the read_isurf command can be written out by the write_surf command, e.g. for visualization purposes. But the file created by this command cannot be read back in to SPARTA via the read_isurf command, because this command creates files in an explicit surface format.

See the Howto 6.13 section of the manual for a discussion of explicit and implicit surfaces as well as distributed versus non-distributed storage of surface elements. You cannot mix explicit and implicit surfaces in the same simulation.

The following optional keywords can be used with this command.

If the points keyword is specified with a value of yes, then a Points section is included in the written file. The Lines or Triangles section will reference indices from the Points section. If the points keyword is specified with a value of no, then a Points section is not included. The Lines or Triangles section will list the coordinates of line segment or trianges corners directly.

If the type keyword is specified, then a surface element type is included for each line or triangle in the Lines or Triangles section. If it is not specified, element types are not incuded.

If the custom keyword is specified along with the name of a custom per-surf vector or array, then the per-surf values for that vector or array are added to the end of the line of output for each line or triangle in the Lines or Triangles section. A per-surf vector is a single value per element; a per-surf array is 1 or more values per element, depending on how it was defined. If the custom keyword is used multiple times, then the value(s) for each name are appended in the order the custom keywords are specified.

The nfile or fileper keywords can be used in conjunction with the "%" wildcard character in the specified surface file name. As explained above, the "%" character causes the surface file to be written in pieces, one piece for each of P processors. By default P = the number of processors the simulation is running on. The nfile or fileper keyword can be used to set P to a smaller value, which can be more efficient when running on a large number of processors.

The nfile keyword sets P to the specified Nf value. For example, if Nf = 4, and the simulation is running on 100 processors, 4 files will be written, by processors 0,25,50,75. Each will collect information from itself and the next 24 processors and write it to a surface file.

For the fileper keyword, the specified value of Np means write one file for every Np processors. For example, if Np = 4, every 4th processor (0,4,8,12,etc) will collect information from itself and the next 3 processors and write it to a surface file.

Restrictions: none

Related commands:

read_surf, read_isurf


The default is points = yes. If the fileper or nfile keywords are not used, a single file is written.