Flexi at a glance

Multiscale Numerics

The Flexi framework is built to solve the unsteady compressible Navier-Stokes equations (and more!) in a highly efficient way.
Target applications are DNS and LES of internal and external compressible flows.

Open and user-friendly

Flexi and its tools are open-source under GPL V3.0, so everybody can enjoy it free of charge. Even better, the clear algorithmic design, the active community and the extensive documentation make it very easy to adapt or extend Flexi to your needs.

Not just a solver

The Flexi framework offers a complete CFD solution, and consists of the high-order mesh generator and preprocessor HOPR, the solver Flexi and a converter to the Paraview format for visualization and postprocessing.

Fully unstructured

Flexi supports fully unstructured curved hexahedral meshes with non-conforming element interfaces, allowing for complex geometries and meshing flexibility. Its preprocessor HOPR can generate curved meshes from a variety of linear meshes from open-source or commercial grid generators.

High-order accurate

Flexi is based on the highly efficient Discontinuous Galerkin Spectral Element Method, allowing you to exploit spectral convergence with very high orders of accuracy. Simulations utilizing O(20) and more are possible.

Massively parallel

The Flexi framework is designed to fully exploit modern parallel architectures up to maximum scale, with actual production runs over 100.000 cores. The solver itself and its I/O scale efficiently to multiple hundred thousand cores, the tool chain allows for parallel post-processing and visualization of huge amounts of data.