sln-slab.1 (6466B)
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If not, see <http://www.gnu.org/licenses/>. 18 .Dd May 5, 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 dhsv 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 d 86 Disables verification of the correspondence between the lines provided 87 by the 88 .Fl l 89 option and those used to construct 90 the acceleration structure defined by the 91 .Fl a 92 option. 93 .Pp 94 Warning! 95 It is always recommended to verify that the data is correct, even though 96 this verification can take a significant amount of time when there are a 97 large number of lines. 98 Anyway, a user who is 99 .Em certain 100 of the data’s consistency may nevertheless use this option 101 .Pq at their own risk 102 to disable this verification and thus speed up the execution. 103 .\"""""""""""""""""""""""""""""""""" 104 .It Fl h 105 Display short help and exit. 106 .It Fl l Ar lines 107 List of lines from which the tree was built. 108 This list is in binary format as generated by the 109 .Xr shtr 1 110 binary, or in plain text HITRAN format, depending on whether the 111 .Fl s 112 option is set or not, respectively. 113 .\"""""""""""""""""""""""""""""""""" 114 .It Fl m Ar molparams 115 Isotopologue metadata in HITRAN format. 116 .\"""""""""""""""""""""""""""""""""" 117 .It Fl n Ar nrealisations 118 Number of Monte Carlo realisations. 119 By default the number of realisations is 10000. 120 .\"""""""""""""""""""""""""""""""""" 121 .It Fl S Ar nu_min , Ns Ar nu_max 122 The spectral range, in cm^-1, over which the computations are performed. 123 The default spectral range is from 0 to infinity. 124 .\"""""""""""""""""""""""""""""""""" 125 .It Fl s 126 Specifies that input lines are formatted according to the binary format 127 as written by the 128 .Xr shtr 1 129 utility, and not according to the HITRAN format. 130 This format is more compact, allowing for faster loading of line data. 131 .\"""""""""""""""""""""""""""""""""" 132 .It Fl T Ar thickness 133 Slab thickness. 134 The default value is 1. 135 .\"""""""""""""""""""""""""""""""""" 136 .It Fl t Ar threads 137 Advice on the number of threads to use. 138 By default, 139 .Nm 140 uses as many threads as processor cores. 141 .\"""""""""""""""""""""""""""""""""" 142 .It Fl v 143 Make 144 .Nm 145 verbose. 146 Multiple 147 .Fl v 148 options increase the verbosity. 149 The maximum is 3. 150 .El 151 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 152 .Sh EXIT STATUS 153 .Ex -std 154 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 155 .Sh EXAMPLES 156 Estimate the transmissivity and emissivity between 100 and 2500 cm^-1 157 for a slab 2 meters thick. 158 The slab consists of a homogeneous gas mixture of H2O, CO2 and CO 159 molecules. 160 The thermodynamic properties of the mixture, such as its pressure, 161 temperature and molecular concentrations, correspond to those used to 162 construct the acceleration structures with sln-build, provided as input 163 arguments 164 .Pq option Fl a . 165 The isotopic metadata 166 .Pq option Fl m 167 and the list of lines 168 .Pq option Fl l 169 partitioned by the acceleration structure, complete the list of input 170 data. 171 The latter is encoded in the format generated by the 172 .Xr shtr 1 173 tool 174 .Pq option Fl s . 175 The isotopes are in HITRAN format. 176 Finally, make the program as verbose as possible 177 .Pq options Fl vvv . 178 .Bd -literal -offset Ds 179 sln-slab -S 100,2500 -T2 -a tree_H2O_CO2_CO_1atm_600K.sln \e 180 -m molparam.txt -sl H2O_CO2_CO_100-2500cm-1.shtr -vvv 181 .Ed 182 .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 183 .Sh SEE ALSO 184 .Xr shtr 1 , 185 .Xr sln-build 1