Paraview - ParaView is an open-source, multi-platform application designed to visualize data sets of size...
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
FreeCAD - An open-source parametric 3D modeler
Gmsh - Gmsh is a 3D finite element grid generator with a build-in CAD engine and post-processor.
meshmixer - meshmixer is an experimental 3D modeling tool for making 3D mashups without too much hassle.
Tecplot 360 - Tecplot 360 is a software package used in post-processing numerical simulation results.