If budget is the primary concern, consider open-source multiphysics engines like OpenFOAM (for fluids), FreeFEM , or FEniCS . Conclusion
It saw a significant boost in performance for segregated solvers and the introduction of better out-of-core solvers for massive models. Comsol Multiphysics 3.5a Free Download
COMSOL is proprietary commercial software. There has never been an official "freeware" version. Any "free download" found on third-party file-sharing sites often involves cracked software, which poses significant security risks (malware/viruses) and is illegal. If budget is the primary concern, consider open-source
Most universities provide COMSOL licenses to students. Check your university’s software portal before seeking out an old, unsupported version. There has never been an official "freeware" version
: Modern versions like COMSOL 4.3 or 5.x can load models saved in 3.5a. However, models from versions older than 3.5 must first be converted to 3.5a format before they can be opened in the latest software. Research Legacy
Currently, downloads for any version of the software are restricted to users with a COMSOL Access account linked to an active, on-subscription license.