FLASH3 Transition: 
The set of implementations of the material properties units provided with FLASH is not comprehensive.
For Heat 
Conductivity and 
Viscosity, we provide implementations
for effects with constant coefficients; these can be used as models for
implementing effects that follow other laws.
For 
MassDiffusivity, only no-operation stubs are provided.
A routine that calculates constant magnetic resistivity and viscosity is provided in the
 
MagneticResistivity unit and can be used in non-ideal magnetohydrodynamics simulations.
Several add-on capabilities are being made available to the users from the 
Download Page on Flash Website.