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NASA Advanced Supercomputing (NAS) Division World-class modeling, simulation, and supercomputing in support of the NASA mission

Chimera Grid Tools

Chimera Grid Tools (CGT) is a software package containing a variety of pre- and post-processing tools for the Chimera overset grid approach for computational fluid dynamics analysis on complex configurations. The CGT package contains a variety of programs and scripts for grid generation, diagnostics, and solution post-processing.

CGT was released in 1999 and used in a wide variety of disciplines including aerospace, marine, automotive, environmental, and sports. The software has been distributed to over 1,000 U.S. organizations in government laboratories, industry, and academia. CGT continues to be regularly updated, and is a mainstay for critical NASA missions today.

Applications range from computational fluid dynamics analysis for the Space Launch System to design studies for existing and next-generation aircraft, including advanced air mobility vehicles.

The package contains a collection of software tools for performing:

  • Geometry processing
  • Surface and volume grid generation
  • Grid manipulation and diagnostics
  • Domain connectivity quality diagnostics and visualization
  • Flow solver input preparation
  • Multi-body dynamics input preparation and animation
  • Flow solution visualization
  • Debris trajectory analysis input preparation
  • Strand grid and AMR Cartesian grid visualization
  • Aerodynamic loads analysis including computation of integrated and sectional forces and moments
  • Convergence history visualization

New Features in CGT Version 3.0

Major updates include:

  • The "Enhanced Procedure for Overset Grid Systems (EPOGS)" toolset for automation of overset structured mesh generation in CFD analyses of aerospace vehicles. This new technology typically reduces the process time from days to hours for simple cases, and from weeks to days for more complex cases.
  • An improved Flexible File I/O in Fortran (FFIO) library for automation of reading and writing of data files used for overset grid CFD analyses, including options for large single block grid I/O using subrecords or binary formats.
  • The “BladeGen" tool for generation of overset grids on rotor blades using the CGT libraries.