Open Source Software
CAD
A parametric 3-D cad modeler, mainly in mechanical engineering and product design. FreeCAD is an on going project. In Debian Linux distributions installation can easily be done from the Ubuntu Software Center.
Finite Elements
A Finite Element software for multi-physics problems. It can solve problems of fluid dynamics, structural mechanics, electromagnetic, heat transfer and acoustics. In Debian Linux distributions installation can easily be done from the Ubuntu Software Center.