The Transport utilities must be used in conjunction with the Gas-phase Kinetics utilities. The general flow of information is depicted in Figure 1.3: Relationships between the CHEMKIN Pre-processors and an Application . The Transport utilities can be used with or without the Surface Kinetics utilities.

As with the Surface Kinetics utilities, the Gas-phase Kinetics Pre-processor must be run prior to the Transport Pre-processor. The Transport Pre-processor requires input from the Transport Database, and from the Gas-phase Kinetics Linking File. The Transport Database contains molecular parameters for a number of species; these parameters are: The Lennard-Jones well depth in Kelvins, the Lennard-Jones collision diameter in Angstroms, the dipole moment in Debyes, the polarizability in cubic angstroms, rotational relaxation collision number and an indicator regarding the nature and geometrical configuration of the molecule. A supplemental input file may also contain this information. The information coming from the Gas-phase Kinetics Linking File contains the species names and molecular weights, as well as thermodynamic data. Like the Gas-phase Kinetics Pre-processor, the Transport Pre-processor produces a Transport Linking File that is later needed in the Transport Subroutine Library.

Both the Gas-phase Kinetics and the Transport Subroutine Libraries must be initialized before use and there is a similar initialization subroutine in each. The Transport Subroutine Library is initialized by a call to subroutine MCINIT. Its purpose is to read the Transport Linking File and populate the storage arrays, allocated by the calling program, which must be made available to all other subroutines in the library. Once initialized, any subroutine in the library may be called from the application program. There are just eighteen (18) subroutines contained in the Transport subroutine library. These return pure-species, binary, and gas-mixture transport properties, using either a mixture-averaged or full multicomponent formulation, as described in the Chemkin Theory Manual Theory Manual.