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Mesh and Data Conversion

In addition to the standard formats (HEC-MW mesh and FSTR analysis control), FrontISTR input/output supports importing external mesh formats and exporting to visualization formats. This chapter summarizes format-conversion functions rather than the computation itself.

Overview of Functions

Data-conversion functions are divided into the following two categories.

Category Function Input/Output
Input-side conversion Import of FEMAP neutral files (neu2fstr) NEU neutral file → HEC-MW mesh + FrontISTR control file
Output-side conversion Export of analysis results to visualization formats (!VISUAL) HEC-MW results → AVS / MicroAVS / FEMAP NEUTRAL / VTK / EXODUS / BMP
Output-side conversion Merging distributed result files from parallel execution (rmerge) Result files for each PE → single result file
Output-side conversion Text/binary conversion of result files (rconv) Text ↔ binary result files

Selection of physical quantities to include in result files and the restart-file mechanism are not covered in this chapter; see Output and Restart.

Importing External Meshes

FrontISTR includes the neu2fstr tool, which converts FEMAP neutral files (NEU) into HEC-MW mesh and FrontISTR control files.

With neu2fstr, the analysis type (static analysis / modal analysis / heat analysis) is specified during conversion. The following files are generated.

  • HEC-MW mesh file: nodal coordinates, element connectivity, material IDs, coordinate systems, node groups, and element groups
  • FrontISTR control file: template of basic control cards such as !SOLUTION, according to the analysis type
  • HEC-MW control file (hecmw_ctrl.dat): generated optionally

When converting for modal analysis, the parameters in the !EIGEN section are provisional values and must be edited by the user after conversion. Information such as boundary conditions, loads, and contact that has no representation in the FEMAP neutral file is not included in the conversion result and must be added to the control file.

Exporting to Visualization Formats

Calculation results can be written to formats for visualization tools in addition to the standard HEC-MW result files. During parallel execution, visualization processing is performed within the same MPI execution as the analysis, so results from all PEs are integrated into a single visualization file.

In the input, !VISUAL,method=PSR specifies pseudo-visualization (cross sections, isosurfaces, deformed shapes, etc.), while !VISUAL,method=PVR specifies volume rendering. See the keyword reference for details of the syntax. The output_type parameter selects from the following formats.

Format Category output_type Value Purpose
AVS UCD (default) AVS Lightweight UCD file containing only surface elements. The default when output_type is omitted.
Complete AVS UCD COMPLETE_AVS, COMPLETE_REORDER_AVS, SEPARATE_COMPLETE_AVS UCD containing all elements. A reordered version (REORDER) and per-PE output version (SEPARATE) can be selected.
Binary AVS UCD BIN_COMPLETE_AVS, BIN_COMPLETE_REORDER_AVS, BIN_SEPARATE_COMPLETE_AVS Binary version of complete AVS UCD.
Compressed AVS UCD COMP_COMPLETE_REORDER_AVS, COMP_SEPARATE_COMPLETE_AVS zlib-compressed version of complete AVS UCD.
MicroAVS COMPLETE_MICROAVS UCD file for MicroAVS.
VTK VTK, BIN_VTK, COMP_VTK VTK format readable by ParaView and similar tools. ASCII / binary / compressed output can be selected.
EXODUS EXODUS, STEP_EXODUS Exodus II format for ParaView. EXODUS writes all time steps to a single file, while STEP_EXODUS writes one file for each time step.
FEMAP NEUTRAL VIS_FEMAP_NEUTRAL, FSTR_FEMAP_NEUTRAL General-purpose text NEUTRAL file in FEMAP format.
BMP image BMP Image of the surface-rendering result (PSR) or volume-rendering result (PVR).

EXODUS format is written only by a FrontISTR executable built with the Exodus II library enabled. Output is skipped in builds where it is disabled.

Merging Parallel Result Files and Type Conversion

To merge result files obtained from parallel execution (split by PE) into a single file without visualization processing, use the rmerge tool. rmerge specifies the number of ranks and the start/end/interval of time steps, and writes a result file in text or binary format.

To convert result files between text and binary representations, use the rconv tool. rconv specifies the start/end/interval of time steps and converts only the representation type.