COMSOL Multiphysics 3.5a is a legacy version of the simulation software, first released around . While it is no longer the current version, it remains relevant for users needing to open older models or run simulations on legacy hardware. Availability and Legality
If you are looking to use COMSOL Multiphysics, avoid any search results promising a "free" version of a non-existent build like "35a." Instead, follow these legitimate paths: comsol multiphysics 35a free new download