Thermal volume (3D) / face (2D) region
Introduction
The volume (in 3D) / face (in 2D) regions are the material regions used to model the massive regions in the study domain.
Material regions (massive regions)
Material massive regions enable the modeling of the material media (with material). The physical properties of a medium are the same as the properties of the material associated with the corresponding region.
A massive region …  enables the modeling …  It is defined by … 

conducting ( + heat source q) 
of a conducting medium* (thermal conductivity k volumetric heat capacity ρCp) 
a material* with: thermal conductivity k volumetric heat capacity ρCp 
with possibly a heat source (uniform or space dependent) 
a thermal power : total value (in W) or volume density (in W/m^{3}) (formula with spatial quantities or formula with input/output parameters) 

for a Steady State Thermal application: only the thermal conductivity k is necessary

for a Transient Thermal application: the thermal conductivity k and the volumetric heat capacity ρCp are necessary
Expression of heat source
In the case, where a heat source exists in the region, this one can be expressed in various ways.
The thermal power of heat source can be expressed by:
 a total value (in W)
 a volume density (in W/m^{3}):
 uniform: constant value or formula with input/output parameters
 space dependent: formula with spatial quantities
Transparency to the thermal radiation
The information about the transparency to the thermal radiation is used only if the local radiation is applied on surfaces (line regions in 2D and surface regions in 3D).
In this case, a radiating surface must be surrounded by an “opaque” volume region in 3D (surface region in 2D) on one side, and a “transparent” region on the other side where the rays can passes.
The choice can be done manually or automatically. The automatic choice makes the inactive regions transparent, and the conducting regions opaque.