Syntax:
compute ID property/surf group-ID input1 input2 ...
possible attributes = id, v1x, v1y, v1z, v2x, v2y, v2z, v3x, v2y, v3z, xc, yc, zc, area, normx, normy, normz
id = surface element ID v1x,v1y,v1z = coords of first line end point or triangle corner point v3x,v2y,v2z = coords of second line end point or triangle corner point v3x,v3y,v3z = coords of third triangle corner point xc,yc,zc = coords of center of line segment or triangle area = length of line segment or area of triangle normx, normy, normz = unit normal vector for line segment or triangle
Examples:
compute 1 property/surf all id xc yc zc
Description:
Define a computation that simply stores surface element attributes for each explicit surface element in a surface group. This is useful for values which can be used by other output commands that take computes as inputs. See for example, the compute reduce, fix ave/surf, dump surf, and surf-style variable commands.
Only surface elements in the surface group specified by group-ID are included in the calculation. See the group surf command for info on how surface elements can be assigned to surface groups.
This command can only be used for simulations with explicit surface elements. Explicit surface elements are triangles for 3d simulations and line segments for 2d simulations. Unlike implicit surface elements, each explicit triangle or line segment may span multiple grid cells. See Section 6.9 of the manual for details.
Id is the surface element ID, as defined in the surface data file read by the read_surf comand.
The v1x, v1y, v1z attributes are the coordinates of the first end point of a line segment (2d) or first corner point of a triangle (3d). Likewise, the v2x, v2y, v2z attributes are the coordinates of the second end point of a line segment (2d) or second corner point of a triangle (3d). The v3x, v3y, v23z attributes are the coordinates of the third corner point of a triangle (3d).
The xc, yc, zc attributes are the coordinates of the center point of a line segment or tringle.
The area attribute is the length of a line segment (distance units in 2d), or area of a triangle (area units in 3d).
The normx, normy, normz attributes are components of a unit normal perpendicular to the line segment or face of the trangle. It points into the flow volume of the simulation.
Output info:
This compute calculates a per-surf vector or per-surf array depending on the number of input values. If a single input is specified, a per-surf vector is produced. If two or more inputs are specified, a per-surf array is produced where the number of columns = the number of inputs.
This compute performs calculations for each explicit surface element in the simulation.
Surface elements not in the specified group-ID will output zeroes for all their values.
The vector or array can be accessed by any command that uses per-surf values from a compute as input. See Section 6.4 for an overview of SPARTA output options.
The vector or array values will be in whatever units the corresponding attribute is in, e.g. distance units for v1x or xc, length units for area in 2d, area units for area in 3d.
Styles with a kk suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed in the Accelerating SPARTA section of the manual. The accelerated styles take the same arguments and should produce the same results, except for different random number, round-off and precision issues.
These accelerated styles are part of the KOKKOS package. They are only enabled if SPARTA was built with that package. See the Making SPARTA section for more info.
You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the -suffix command-line switch when you invoke SPARTA, or you can use the suffix command in your input script.
See the Accelerating SPARTA section of the manual for more instructions on how to use the accelerated styles effectively.
Restrictions:
For 2d simulations, none of the attributes which refer to the 3rd dimension may be used. Likewise v3x, v3y, v3z may not be used since they refer to triangles.
Related commands:
Default: none