compute ID react/boundary reaction-ID value1 value2 ...
r: or p: = list of reactant species or product species s1,s2,s3 = one or more species IDs, separated by "/" character
surf_react air prob air.surf compute 1 react/boundary air compute 2 react/boundary air r:N/O/N2/O2 p:N/O/NO
These commands will time average the reaction tallies for each face and output the results as part of statistical output:
compute 2 react/boundary air r:N/O/N2/O2 p:N/O/NO
fix 1 ave/time all 10 100 1000 c_2[*] stats_style step np f_1[*] f_1[*] f_1[*] f_1[*]
Define a computation that tallies counts of reactions for each boundary (i.e. face) of the simulation box, based on the particles that collide with the boundary. Only faces assigned to the surface reaction model specified by reaction-ID are included in the tallying.
Note that when a particle collides with a face, it can bounce off (possibly as a different species), be captured by the surface (vanish), or a 2nd particle can also be emitted.
The doc page for the surf_react command explains the different reactions that can occur for each specified style.
If no values are specified each reaction specified by the surf_react style is tallied individually for each boundary.
If M values are specified, then M tallies are made for each face, one per value. If the value starts with "r:" then any reaction which occurs with one (or more) of the listed species as a reactant is counted as part of that tally. If the value starts with "p:" then any reaction which occurs with one (or more) of the listed species as a product is counted as part of that tally. Note that these rules mean that a single reaction may be tallied multiple times depending on which values it matches.
The results of this compute can be used by different commands in different ways. The values for a single timestep can be output by the stats_style command. The values over many sampling timesteps can be averaged by the fix ave/time command.
This compute calculates a global array, with the number of columns either equal to the number of reactions defined by the surf_react style (if no values are specified) or equal to M = the # of values specified. The number of rows is 4 for a 2d simulation for the 4 faces (xlo, xhi, ylo, yhi), and it is 6 for a 3d simulation (xlo, xhi, ylo, yhi, zlo, zhi).
The array can be accessed by any command that uses global array values from a compute as input. See Section 6.4 for an overview of SPARTA output options.
The array values are counts of the number of reactions that occurred on each face.
fix ave/time, compute react/surf