7 Fixed External Sources

A fixed external source in Radiant is represented by the Radiant.Fixed_Sources object. Once instantiated, the user can add two kinds of source to it using

s = Fixed_Sources(cs,geo,solvers)     # Instantiation using cross-sections, geometry and solver object
s.add_source(surface_source)          # Adding a surface source
s.add_source(volume_source)           # Adding a volume source

where surface_source and volume_source are respectively Radiant.Surface_Source and Radiant.Volume_Source objects defined in the following sections.

7.1 Surface Sources

A surface source is represented by the Radiant.Surface_Source object. It is defined on a boundary of the geometry. For Cartesian geometry, these boundaries are identified as x-, x+, y-, y+, z- and z+. It should be noted that the surface source is associated with the given particle ID. In 1D Cartesian geometry, the definition of the surface source can take this form

ss = Surface_Source()
ss.set_particle(photon)            # Set the particle
ss.set_intensity(1.0)              # Set the source intensity
ss.set_energy_group(1)             # Set the energy group
ss.set_direction([1.0,0.0,0.0])    # Set the direction using direction cosine
ss.set_location("X-")              # Set location of the source

In 2D or 3D geometry, an additionnal term has to be added to define the size of the source on the given boundary. For example, in 2D Cartesian geometry, taking the same example, the user should add

ss.set_boundaries("y",[2.0,3.0])   # Set the boundaries of the source along axis y

7.2 Volume Sources

A surface source is represented by the Radiant.Volume_Source object. It is defined within the geometry domain. For 1D Cartesian geometry, a volume source can be defined as

vs = Volume_Source()
vs.set_particle(photon)
vs.set_intensity(1.0)
vs.set_energy_group(1)
vs.set_boundaries("x",[0.0,2.0])

and similarly for 2D and 3D Cartesian geometry, adding boundaries along y and z axis.