In OpenFOAM, the Computational Fluid Dynamics (CFD) solver, data files do not have a single standard file suffix like other software. Instead, OpenFOAM organizes data in directories and specific file types based on simulation cases.

Common OpenFOAM File Types and Suffixes

File Type	Suffix / Format	Description
Case Files	(no fixed suffix, folder-based)	OpenFOAM cases are stored in directories (caseName/)
Mesh Files	.obj, .stl, .msh, .foam	Mesh files from external sources (STL for surface meshes, MSH for Fluent/Gambit)
Control Dictionary	controlDict (no suffix)	Main simulation control file (system/controlDict)
Boundary Conditions	.U, .p, .T (no suffix)	Initial and boundary condition files inside 0/ directory
Solver Executables	(no suffix, Linux binary)	Solvers like simpleFoam, pisoFoam, icoFoam
Post-Processing Files	.vtk, .vtu, .foam, .csv	Output files for visualization in ParaView or Tecplot
Time-Step Data	(numeric directories, e.g., 100, 200)	Simulation output stored in time folders
Decomposed Cases	processorX/ directories	Files for parallel processing (processor0/, processor1/, etc.)

Key Notes

• OpenFOAM is directory-based, meaning case files are not stored as .dat or .txt files like Fluent or Abaqus.
• .foam files are often used to load OpenFOAM cases into ParaView for visualization.
• Mesh data can be imported/exported in STL, OBJ, or MSH formats.