sln-slab.1 (5836B)
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If not, see <http://www.gnu.org/licenses/>. 18 .Dd March 23, 2026 19 .Dt SLN-SLAB 1 20 .Os 21 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 22 .Sh NAME 23 .Nm sln-slab 24 .Nd computations of radiative transfer in a 1D homogeneous slab 25 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 26 .Sh SYNOPSIS 27 .Nm 28 .Op Fl hsv 29 .Op Fl n Ar nrealisations 30 .Op Fl T Ar thickness 31 .Op Fl t Ar threads 32 .Fl S Ar nu_min , Ns Ar nu_max 33 .Fl a Ar accel_struct 34 .Fl m Ar molparams 35 .Fl l Ar lines 36 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 37 .Sh DESCRIPTION 38 .Nm 39 calculates the transmissivity and the emissivity in a one-dimensional 40 homogeneous slab of arbitrary thickness using a Monte Carlo algorithm 41 that samples the spectral lines that make up the gas mixture. 42 These computations are accelerated by sampling the lines based on the 43 magnitude of their contribution to the mixture’s spectrum, so that few 44 Monte Carlo runs are required to estimate the transmissivity with a high 45 degree of confidence. 46 The core of the proposal rests on this sampling strategy, made possible 47 by constructing an acceleration structure from the set of lines in the 48 mixture. 49 A structure built using the 50 .Xr sln-build 1 51 utility and provided as input to the program. 52 .Pp 53 More than just a numerical simulation tool, 54 .Nm 55 is primarily designed to validate the aforementioned acceleration 56 structure in relation to its intended use, namely radiative transfer 57 computations. 58 Thus, not only could an error be returned in the event of a problem with 59 the structure or its use, but the computed value can also contribute to 60 this validation through its comparison with the result of a computation 61 of the same quantity performed by another radiative transfer code. 62 .Pp 63 The output of 64 .Nm 65 displays the estimated transmissivity and emissivity, their standard 66 deviation, and the number of Monte Carlo realisations rejected due to 67 issues encountered during the computation, such as numerical 68 uncertainty. 69 Each estimate is displayed on a line formatted as follows: 70 .Bd -literal -offset Ds 71 "%-16s: %e +/- %e; %lu\en", name, estimate, std_err, rejects_count 72 .Ed 73 .Pp 74 The options are as follows: 75 .Bl -tag -width Ds 76 .\"""""""""""""""""""""""""""""""""" 77 .It Fl a Ar accel_struct 78 An acceleration structure corresponding to the input 79 .Ar lines , 80 used to accelerate their sampling based on their importance. 81 This structure is generated by the 82 .Xr sln-build 1 83 tool. 84 .\"""""""""""""""""""""""""""""""""" 85 .It Fl h 86 Display short help and exit. 87 .It Fl l Ar lines 88 List of lines from which the tree was built. 89 This list is in binary format as generated by the 90 .Xr shtr 1 91 binary, or in plain text HITRAN format, depending on whether the 92 .Fl s 93 option is set or not, respectively. 94 .\"""""""""""""""""""""""""""""""""" 95 .It Fl m Ar molparams 96 Isotopologue metadata in HITRAN format. 97 .\"""""""""""""""""""""""""""""""""" 98 .It Fl n Ar nrealisations 99 Number of Monte Carlo realisations. 100 By default the number of realisations is 10000. 101 .\"""""""""""""""""""""""""""""""""" 102 .It Fl S Ar nu_min , Ns Ar nu_max 103 The spectral range, in cm^-1, over which the computations are performed. 104 .\"""""""""""""""""""""""""""""""""" 105 .It Fl s 106 Specifies that input lines are formatted according to the binary format 107 as written by the 108 .Xr shtr 1 109 utility, and not according to the HITRAN format. 110 This format is more compact, allowing for faster loading of line data. 111 .\"""""""""""""""""""""""""""""""""" 112 .It Fl T Ar thickness 113 Slab thickness. 114 The default value is 1. 115 .\"""""""""""""""""""""""""""""""""" 116 .It Fl t Ar threads 117 Advice on the number of threads to use. 118 By default, 119 .Nm 120 uses as many threads as processor cores. 121 .\"""""""""""""""""""""""""""""""""" 122 .It Fl v 123 Make 124 .Nm 125 verbose. 126 Multiple 127 .Fl v 128 options increase the verbosity. 129 The maximum is 3. 130 .El 131 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 132 .Sh EXIT STATUS 133 .Ex -std 134 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 135 .Sh EXAMPLES 136 Estimate the transmissivity and emissivity between 100 and 2500 cm^-1 137 for a slab 2 meters thick. 138 The slab consists of a homogeneous gas mixture of H2O, CO2 and CO 139 molecules. 140 The thermodynamic properties of the mixture, such as its pressure, 141 temperature and molecular concentrations, correspond to those used to 142 construct the acceleration structures with sln-build, provided as input 143 arguments 144 .Pq option Fl a . 145 The isotopic metadata 146 .Pq option Fl m 147 and the list of lines 148 .Pq option Fl l 149 partitioned by the acceleration structure, complete the list of input 150 data. 151 The latter is encoded in the format generated by the 152 .Xr shtr 1 153 tool 154 .Pq option Fl s . 155 The isotopes are in HITRAN format. 156 Finally, make the program as verbose as possible 157 .Pq options Fl vvv . 158 .Bd -literal -offset Ds 159 sln-slab -S 100,2500 -T2 -a tree_H2O_CO2_CO_1atm_600K.sln \e 160 -m molparam.txt -sl H2O_CO2_CO_100-2500cm-1.shtr -vvv 161 .Ed 162 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 163 .Sh SEE ALSO 164 .Xr shtr 1 , 165 .Xr sln-build 1