The CGNS system

Abstract

The CGNS system consists of a collection of conventions, and confonning software, for the storage and retrieval of Computational Fluid Dynamics (CFD) data It facilitates the exchange of data between sites and applications, and helps stabilize the archiving of aerodynamic data The data are stored in a compact, binary format and are accessible through a complete and extensible library of functions. This API (Application Program Interface) is platform independent and can be easily implemented in C, C++, Fortran and Fortran90 applications. The CGNS system supports structured, unstructured and mixed topology, where multi-block connectivity may be either one-to-one abutting, mismatched abutting or overset It defines standards for the storage of grid coordinates, flow solutions, boundary conditions, convergence history, reference state and geometry data. Dimensional units and nondimensionalization information may be associated with each type of data. Additionally, it provides conventions for archiving the governing equations including the gas, viscosity, thermal conductivity, turbulence and diffusion models. The CGNS system can be extended to other types of engineering analysis data, and serve multi-disciplinary applications. It is offered to the CFD community for the purpose of establishing a standard for aerodynamic data storage. This paper presents the different components of the CGNS system, from the essence of its constituents to its supporting data structures and software capacity. It demonstrates the facility to implement the CGNS system through a series of short examples, followed by a review of its incorporation into both research and commercial CFD applications.