What is traditional
physics-based simulation?
Before robots learned in simulators, engineers were already simulating physics: how air flows around a car, how heat spreads through a motor, how a bracket bends under load. This is traditional physics-based simulation. It is slow, precise and trusted, and it is the reference that everything faster is measured against.
How it works
Air, water, heat and stress are continuous: they exist at every point of a volume. To compute them, the software divides the volume into a mesh of small cells and tracks how quantities such as mass, heat or force pass from each cell to its neighbours. A TU Delft engineering textbook describes the most common version, the finite volume method, in exactly these terms.[10] The finer the mesh, the more accurate and the slower the result.
The two big families
CFD (computational fluid dynamics) simulates gases and liquids, and usually heat with them. Examples: OpenFOAM, Siemens Simcenter STAR-CCM+ and Ansys Fluent.[1][3][6] This is what Invisible Force uses to model air leaking into a vacuum gripper.
FEA (finite element analysis) simulates solid parts: how they bend, vibrate, heat up or break. Examples: Ansys Mechanical, CalculiX and FEniCS.[6][8][9] A related family simulates electromagnetic fields, such as Ansys Maxwell, which is the kind of tool used to study a magnetic gripper.[6]
Multiphysics tools such as COMSOL combine several of these in one model, for instance heat and electric current in a motor winding.[7]
The tools, as of 2026
| Tool | Maker | Domain | Latest release |
|---|---|---|---|
| OpenFOAM | OpenFOAM Foundation and OpenCFD (open source) | Fluids, heat | Version 14, July 2026; v2606, June 2026[1][2] |
| Simcenter STAR-CCM+ | Siemens | Fluids, heat, multiphysics | 2606, July 2026[3][4] |
| Ansys Fluent, Mechanical, Maxwell | Ansys (Synopsys) | Fluids, structures, electromagnetics | 2026 R1, March 2026[5][6] |
| COMSOL Multiphysics | COMSOL | Multiphysics | 6.4, November 2025[7] |
| CalculiX, FEniCS | Open source | Structures, general equations | CalculiX 2.23, November 2025; DOLFINx 0.11, June 2025[8][9] |
Why it matters for robots
These tools are too slow to run inside a robot simulator that steps a thousand times per second. But they are the ground truth. The physics that Invisible Force adds to robot simulators, such as heat in a motor or air in a suction cup, is checked against this kind of software, and increasingly replaced by fast approximations learned from it. See What is AI-accelerated physics?
References
- The OpenFOAM Foundation. OpenFOAM 14 release. July 2026.
- OpenCFD (Keysight). OpenFOAM v2606 release notes. June 2026.
- Siemens. Simcenter STAR-CCM+ product page. 2026.
- Siemens Simcenter blog. What's new in Simcenter STAR-CCM+ 2606. July 2026.
- Ansys (Synopsys). Ansys 2026 R1 release highlights. March 2026.
- Ansys (Synopsys). Ansys Fluent, Ansys Mechanical and Ansys Maxwell product pages. 2026.
- COMSOL. COMSOL Multiphysics 6.4 release. November 2025.
- Dhondt and Wittig. CalculiX: a free finite element program. November 2025.
- FEniCS Project. FEniCS project and DOLFINx 0.11.0 release. June 2025.
- TU Delft. PDEs and the Finite Volume Method (MUDE textbook). 2024.
Every link was opened and checked in September 2026. Links open in a new tab.