Flitzr is a set of plug-in components for OpenFOAM. They replace the performance-critical parts of a run – linear solvers, matrix ordering, mesh partitioning, I/O – with faster implementations. Your case stays the same; we validate the results against your acceptance criteria. Flitzr works with any hardware vendor and any OpenFOAM flavour.
What it speeds up
- Memory bandwidth, the usual bottleneck of CFD on CPUs: improved computational kernels and cache-aware matrix renumbering.
- Parallel efficiency: topology-aware mesh partitioning and non-blocking asynchronous linear solvers that spend less time waiting for communication.
- I/O: parallel and asynchronous reading and writing.
- Load balance on several levels.
Where it helps, we add optimised solver settings, hardware-specific tuning, asynchronous GPU offloading of selected parts, and optimisation loops with AI.
Example: DrivAer car aerodynamics
The DrivAer case of the OpenFOAM HPC Technical Committee (external aerodynamics with simpleFoam) is the benchmark of the OpenFOAM HPC Challenge. In the second challenge, OHC-2, it ran with Flitzr up to 3.75× faster on 65 million cells and up to 4.64× faster on 236 million cells than standard OpenFOAM v2512 with default settings on the same hardware: compute nodes with AMD EPYC processors of the third generation (“Milan”).
| Partitions | 65 million cells | 236 million cells |
|---|---|---|
| 128 | 2.75× | |
| 256 | 2.90× | |
| 512 | 3.06× | 3.01× |
| 1024 | 3.52× | 3.38× |
| 2048 | 3.47× | 3.56× |
| 4096 | 3.49× | 4.64× |
| 8192 | 3.75× | 4.22× |
Try it on your case, free of charge
- You send us your case, how you run it, the target platform and your acceptance criteria – optionally also access to your hardware and a non-binding indication of your budget.
- We analyse it with profiling tools (Score-P, Extrae, likwid, perf, down to the assembly code), add the components that help, and measure the speed-up with statistical methods.
- You get the overall speed-up, validated against your criteria, and what achieved it.
- For production use, we agree on the transfer and licensing of the components.