SimFlow - SimFlow is a powerful CFD software, focused on engineering and science.
FreeCAD - An open-source parametric 3D modeler
COMSOL Multiphysics - COMSOL is the developer of COMSOL Multiphysics software, an interactive environment for modeling and simulating scientific and engineering problems.
SketchUp - 3D for Everyone
ANSYS Fluent - ANSYS engineering simulation and 3D design software delivers product modeling solutions with unmatched scalability and a comprehensive multiphysics foundation.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.