In the MFiX 19.2 online user guide, the unit of the reaction rate for DEM/PIC should be specified more clearly. “…usr_rates_des.f must have units of reacted moles per time (i.e., moles/sec)”, this sentence is not clear, should be rephrased to " …usr_rates_des.f must have units of reacted moles per time (i.e., moles/sec for CGS units and kmoles/sec for SI units)" to keep consistent with the description of rate units for TFM.
4.13.3.4.1. Reaction Rates
Define chemical reaction rates in user defined function (UDF) files.
A reaction rate should be given in either usr_rates.f or usr_rates_des.f for each reaction listed in the data file.
All TFM gas and solids phase reactions as well as homogeneous gas phase reactions for DEM simulations are to be included in usr_rates.f. Reaction rates defined in usr_rates.f must have units of reacted moles per time per volume (i.e., moles/sec/cm3 for CGS units and kmoles/sec/m3 for SI units).
All discrete phase heterogeneous (particle/gas) reactions are to be included in usr_rates_des.f located in the des subfolder. Reaction rates defined in usr_rates_des.f must have units of reacted moles per time (i.e., moles/sec).