LIGGGHTS 2.1: (released 30 August 2012)
+ Added a big SPH patch from Andreas Aigner (JKU) with improved efficiency and numerics for SPH. Also added a new SPH example
+ Included some re-work by Philippe Seil (JKU) for the particle-mesh distance algorithm where corner contacts were not detected correctly in rare cases. Thanks to Tapan Sabuwala (U Illinois) for posting an example that showed this.
+ Added support to specify the list of meshes to be dumped by the dump/mesh/stl and dump/mesh/vtk commands, rather than dumping all meshes in the simulation automatically.
+ Added an improved restart logic to fix move/mesh/linear/variable and fix move/mesh/rotate/variable.
+ Fixed an issue with superposition of two rotation commands that work with the same rotation axis. Thanks to Christian Richter (OVGU) for pointing out there was an issue.
+ Fixed a small glitch in the new "output" option of the dump mesh/VTK command. Thanks to Philippe Seil (JKU) and Christian Richter (OVGU) for noting this.
However, there are some restrictions in 2.1 (see below) which will be relaxed over time:
+ region tetmesh is not yet available
+ 'all_in yes' is not yet available for fix insert/stream
+ fix breakparticle/force is not yet available