# VELOCITY

I/O Options and Subcase Information Entry The VELOCITY command can be used in the I/O Options or Subcase Information sections to request velocity vector output for all subcases or individual subcases, respectively.

## Format

VELOCITY(sorting,format,form,rotations,random,peakoutput,type,fourier,statistics) = option

## Definitions

Argument Options Description
sorting <SORT1, SORT2> This argument only applies to the PUNCH format (.pch file) or the OUTPUT2 format (.op2 file) output for normal modes, frequency response, and transient subcases. It will be ignored without warning, if used elsewhere.
SORT1
Results for each frequency/ timestep are grouped together.
SORT2
Results for each grid/element are grouped together. 7
blank (Default)
For Frequency Response Analysis, if grid SET is not specified, SORT1 is used, otherwise, SORT2 is used; for Transient Analysis, SORT2 is used.
format <HM, H3D, OPTI,PUNCH, OP2, HG, PLOT, HDF5, blank>

Default = blank

HM
Results are output in HyperMesh results format (.res file).
H3D
Results are output in Hyper3D format (.h3d file).
OPTI
Results are output in OptiStruct results format (.disp file).
PUNCH
Results are output in Nastran punch results format (.pch file).
OP2
Results are output in Nastran output2 format (.op2 file).10
HG
Results are output in HyperGraph presentation format (_freq.mvw file and _tran.mvw file) - see OUTPUT keywords HGFREQ and HGTRANS.
PLOT
Results are output in Nastran output2 format (.op2 file) when PARAM,POST is defined in the Bulk Data section.
If PARAM, POST is not defined in the Bulk Data section, this format allows the form for complex results to be defined for XYPUNCH output without having other output.
HDF5
Results are output in the Hierarchical Data Format, Version 5 (.h5 file). 14
blank
Results are output in all active formats for which the result is available.
form <COMPLEX, REAL, IMAG, PHASE, BOTH>

Default (HM only) = COMPLEX

Default (all other formats) = REAL

COMPLEX (HM only), blank
Provides a combined magnitude/phase form of complex output to the .res file for the HM output format.
REAL or IMAG
Provides rectangular format (real and imaginary) of complex output. 8
PHASE
Provides polar format (magnitude and phase) of complex output. Phase output is in degrees. 8
BOTH (HM only)
Provides both polar and rectangular formats of complex output.
rotations <ROTA, NOROTA>
ROTA
Requests rotational velocity output results (in addition to rotational velocity results).
NOROTA (Default)
Rotational velocity results are not output.
random <PSDF, RMS, PSDFC>

No default

Output is available in the .h3d, and .h5 formats. 5
PSDF
Requests PSD and RMS results from Random Response Analysis to be output.
RMS
Requests only the RMS result from Random Response Analysis to be output.
PSDFC
Requests PSD, RMS and RMS (cumulative) results from random response analysis to be output.
peakoutput <PEAKOUT>

Default = blank

If PEAKOUT is present, only the filtered frequencies from the PEAKOUT card will be considered for this output.
type <NORMAL>
NORMAL
If present, the normal velocity results for grids on the surface of shell and solid elements are output. 12
blank (Default)
Normal velocity results are not output.
FOURIER <FOURIER>
FREQ
If present, velocities in the frequency domain are output for Modal Transient Response Analysis with Fourier Transformation.13
TIME
If present, velocities in the time domain are output for Modal Transient Response Analysis with Fourier Transformation. 13
blank (Default)
statistics <STATIS, OSTATIS, or blank> Results of Velocity Statistics over time in a Transient Analysis are controlled by this option. 15
STATIS
Velocity statistics are output in addition to regular velocity output at each timestep.
OSTATIS
Only the Velocity statistics are output.
blank (Default)
option <YES, ALL, NO, NONE, SID>

Default = YES

YES, ALL, blank
Velocity is output for all nodes.
NO, NONE
Velocity is not output.
SID
If a set ID is given, velocity is output only for nodes listed in that set.

1. When the VELOCITY command is not present, velocity vector is not output.
2. Velocity output is available for frequency response and transient analysis solution sequences.

Velocity output is available by default for Darcy Flow Analysis subcases and can be controlled using the VELOCITY command. Velocity for flow analysis is only available in H3D files and can be visualized as “Element Velocity for Flow (v)” in HyperView.

For Darcy Flow Analysis:
• VELOCITY I/O Entry accepts either YES/ALL or GRID SETs as input.
• For Darcy flow, any elements attached to the GRID IDs in the specified GRID SET will have their elemental velocity output printed.
• ELEMENT SET based identification is not supported for the VELOCITY I/O Entry.
• In the example illustrated below, choosing SET 12 for VELOCITY results will output Darcy flow velocity for the following 8 CHEXA elements.
VELOCITY = 12
BEGIN BULK
SET,12,GRID,LIST
+, 3802, 9452

3. The form argument is only applicable for Frequency Response Analysis. It is ignored for other analysis types.
4. The forms BOTH and COMPLEX do not apply to the .frf output files.
5. Multiple formats are allowed on the same entry; these should be comma separated. If a format is not specified, this output control applies to all formats defined by the OUTPUT command, for which the result is available. See Results Output by OptiStruct for information on the results available and their respective formats.
6. Multiple instances of this card are allowed. If instances are conflicting, the last instance dominates.
7. For optimization, the frequency of output to a given format is controlled by the I/O option OUTPUT.
8. In general, HyperView does not recognize the SORT2 format for results from the .op2 file. When results are output only in SORT2 format (<Result Keyword> (SORT2, OUTPUT2, ...)), the results are written by OptiStruct into the .op2 file in SORT2 format, but when the .op2 file is imported into HyperView, the results in SORT2 format are not recognized. Therefore, the SORT1 option is recommended for results output in OUTPUT2 format and SORT2 option is recommended for results output in PUNCH format.
9. Results in binary format (.h3d or .op2) are always output in PHASE/MAG form, regardless of the options specified in the FORM field. The corresponding post-processors ( HyperView/ HyperGraph) can easily convert the PHASE/IMAG format to the required formats. Results in ASCII formats are output in the specified/requested FORM.
10. The four-letter abbreviation VELO is interchangeable with VELOCITY.
11. format=OUTPUT2 can also be used to request results to be output in the Nastran output2 format (.op2 file).
12. For NORMAL velocity output, the surface grids are automatically selected from within the specified GRID SET. Alternately, if option=ALL is input, the normal velocity is output for all surface grids in the model. Normal results are only available for Frequency Response Analysis and in the H3D format.
13. The FREQ and TIME options are only valid for Modal Transient Analysis with Fourier transformation. When FREQ is present, the velocities in frequency domain would be output in a dummy frequency subcase, which shares the same ID with the transient subcase.
14. The HDF5 output is printed to a .h5 binary results file. For details of the supported analysis types and elements when the .h5 output format is requested, refer to the .h5 file.

For details about the old HDF5 format (.hdf5), refer to PARAM, HDF5 and .hdf5 file.

15. Velocity statistics are supported for Direct and Modal Linear Transient Analysis types.

Only H3D output is supported for velocity statistics.

The following statistics over time are output for Transient Analysis when STATIS or is specified.
Statistics
Supported Velocity Result Types
Minimum and Time of Minimum
X-component, Y-component, Z-component
Maximum and Time of Maximum
Magnitude, X-component, Y-component, Z-component
Absolute Maximum and Time of Absolute Maximum
X-component, Y-component, Z-component
Arithmetic Mean, Root Mean Square (RMS), Variance, and Standard Deviation
Magnitude, X-component, Y-component, Z-component
The velocity statistics can be viewed in HyperView after loading the H3D file, under Statistics over time option at the end of the timestep list in the Results Browser. Then, various statistics can be chosen from the sub-menu under Velocity (Statistics) (s).