NaysDw2 is a solver in iRIC for tracking driftwoods using material tracking functions of UTT.
The method used in NaysDw2 is the same as UTT which is the Lagrangian method of tracing materials.
NaysDw2 also has a function of hitting and rotating materials to each other as the DEM method.

online manual is here
for iRIC v4
for iRIC v3