What is Cassiopee?

A set of Python modules for CFD pre- and post-processing

Cassiopee (CFD Advanced Set of Services In an Open Python EnvironmEnt) is a set of Python modules providing advanced services for preparing CFD computations and post-processing CFD solutions. This is a research software developped by Onera, the French Aerospace Lab and distributed as free software under GPL3. Cassiopee is independent of any solver and can be used with any multiblock/overset structured/unstructured flow solver.
Provided services are low level functions, that are designed to be used for easily building your own applications.
Basically, all modules can manipulate two open data types (see Converter introduction): the first one is called an array and is a direct encapsulation of a numpy array. The second one is called the CGNS Python tree. CGNS is a data model enabling the description of a numerical simulation case. CGNS is now widely used in the CFD community for exchanging data between the various softwares of a simulation pipeline (mesh generators, flow/structure/thermal solvers, post-processing tools).
The package contains the following Python modules among others:

• Converter: read/write arrays/CGNS Python trees to various file formats, such as Voir3D, Plot3d, Tecplot, CGNS/ADF, CGNS/HDF...
• Geom: create basic surfaces such as bezier, splines, ...
• Transform: perform grid transformations.
• Generator: provide basic grid generation functions and more advanced features.
• Intersector: provide mesh intersection algorithms.
• Connector: perform grid connectivity. Automatic matching boundaries detection, Overset grid assembly (blanking, interpolation cell search, ...)
• Initiator: provide solution initialization functions.
• Post: perform solution post-processing (streamLines, slices, isosurfaces, integration...)
• Dist2Walls: compute distance to bodies.
• RigidMotion: enable definition of rigid motions.
• Compressor: enable CFD field in memory compression.
• Distributor2: enable mesh distribution over processors.
• CPlot: display mesh and solution to screen or image/movie files.

All module functions are of course usable in Python scripts. In addition, a graphical user interface enabling to access the major modules functions [see Fig] is also available. These modules are successfully used for fixed wing, helicopter, propeller and turbomachninary complex applications.