In this part of the parameter file the radiation transport module has to be selected. Depending on this selection a couple of additional parameters have to be specified. Table 12 gives a list of the parameters and the modules they apply to. The standard routines are now in the MSrad module for local models and the SHORTrad module for global ``Star-in-a-Box'' models. The LHDrad module is not maintained very much anymore.
None: Skip radiation transport entirely.
LHDrad: (old ``supergiant module'') It uses long characteristics and is restricted to an equidistant grid and open boundaries at all surfaces. Note that the switch
-Drhd_r01=1has to be set during compilation (see Sect. 3.7).
MSrad: (``solar module'') It uses long characteristics. The lateral boundaries have to be periodic. Top and bottom can be closed or open. Note that the switch
-Drhd_r02=1has to be set during compilation (see Sect. 3.7).
SHORTrad: (new ``supergiant module'') It uses short characteristics and is restricted to an equidistant grid and open boundaries at all surfaces. Note that the switch
-Drhd_r03=1has to be set during compilation (see Sect. 3.7).
1. In the implicit case it is set to a higher value (typically
n_raditeriterations will (probably) needed. The parameter can be set e.g. with
1. For starts with shorter radiative time scales values around
10may be considered. All three radiation transport modules understand this parameter.
n_radmaxiterwill either be set to a values somewhat larger than the recommended number of iterations (
n_raditer) or to
0which disable the check for too many iterations completely. This can be safely allowed in many cases and has the advantage that there is no need to save the initial model before calling the radiation transport module, which saves some memory. To disable the iteration of the radiation transport sub-step set
1. All three radiation transport modules understand this parameter.
SHORTradthe orientation of the base axis system can be selected e.g. with
unity: (default) During all time steps and radiative sub-steps the direction of the rays stays the same.
random: At each time step (and radiative sub-step) a new base axis system is chosen at random
randomgroup: At each new time step a new base axis system is chosen at random. It is kept for all radiative sub-steps.
radraystar) it is advisable to vary the directions of the rays (by choosing
randomgroup) to cover the entire sphere at least over a longer time.
SHORTradthe list of ray directions (i.e. the number of rays and their coordinates) relative to the base axis system can be specified with e.g.
x1: (N=1) one single ray along x1 axis (not enough to specify fluxes in all directions)
x2: (N=1) one single ray along x2 axis (not enough to specify fluxes in all directions)
x3: (N=1) one single ray along x3 axis (not enough to specify fluxes in all directions)
oktaeder: (N=3, default) octahedron
tetraeder: (N=4) tetrahedron
ikosaeder: (N=6) icosahedron
dodekaeder: (N=10) dodecahedron
list-01(3): Choose ray systems from a list (oktahedrons, tetrahedrons). If
character radraybaseis set to
unitythe rays will only be aligned to the axes or diagonals and thus avoid the time-consuming interpolation step of the short-characteristics method.
MSradmodule the ray directions have to specified in a different way: The number of ray sets in theta direction can be chosen with e.g.
MSradmodule the number of ray sets in phi direction can be set e.g. with
MSradmodule the number of rays per cell (with the same direction) can be specified e.g. with
MSradmodule the lower part of the model can be computed in diffusion approximation. The number of points in diffusion approximation can be set with e.g.
0means that the diffusion approximation is not used in any part of the model.
MSradmodule the number of points on the rays can be finer than the number of points in the basic numerical grid. The refinement can be set e.g. with
1: Use the grey part of the table
2: Use the other (possibly non-grey, frequency-dependent) part of the table
MSradmodule so far can handle non-grey tables.
SHORTradmodule (tentatively) support implicit radiation transport. It can be activated with the parameter
0.0: Fully explicit radiation transport (possible with all modules)
1.0: Partly implicit radiation transport
0.5: Radiation transport time-centered
1.0: Fully implicit radiation transport
LHDradmodule only) the requested convergence accuracy of the iteration can be set e.g. with
LHDradmodule only) the step size of the iteration can be restricted with e.g.
1.0: Restricted step size
1.0: No restriction, standard step size
1.0: Extra large steps
LHDradmodule the limit in delta optical depth (rho*kappa*dx) below which the ``radiative temperature viscosity'' (=temperature smoothing) is to be applied can be set with e.g.
LHDradmodule the amount of the ``radiative temperature viscosity'' (=temperature smoothing) can be specified e.g. with
0.0). But often its use is necessary.