CHEMKIN Interface

CHEMKIN INTERFACE

6. Additional Print-out

It is useful, indeed it is often the reason to perform a simulation, to be able to print-out and to plot reaction rates, rates of production of species, the heat-release rate, and the elemental composition. The print-out is activated as follows:

STORE(QDOT)	- activates storage and print-out of heat- release rate in erg/s/cm^3.
STORE(Cn+)	- activates storage and print-out of the rate of production of concentration Cn, eg. STORE(C12+) for rate of production of C12
STORE(n&)	- activates storage and print-out of the rate of reaction n, eg. STORE(4&) for rate of reaction 4
STORE(ELxx)	- activates storage and print-out of the mass composition of element xx, eg. STORE(ELN) for nitrogen

In addition, the elemental composition is printed at the monitor point whenever the monitor data is printed.

The elemental composition is calculated as follows:

Ej = sum (Ajk*Wj*Yk/Wk)

where the summation is over all species k, Ej is the mass composition of element j, Aij is the number of atoms of the element j in the kth species, Yk is the mass fraction of species k, Wj is the molecular mass of element k, and Wk is the molecular mass of species k.

Mole-fractions are computed and printed at completion, and whenever the NPRINT settings etc. indicate that the STOREd dependent variables are to be printed. The mole-fraction print-out is always generated, and does not require storage of extra variables.

However, if desired, the user may STORE the mole fractions for printing in the RESULT file and also for plotting purposes with PHOTON and AUTOPLOT. This facility is activated by setting:

STORE(Mxxx)

which activates storage and print-out of the mole fraction of the species xx, eg. STORE(MH2) for the SOLVEd hydrogen species H2.

The mole fractions Xi are calculated from:

Xi = Yi*W/Wi

where W is the mixture molecular mass, and Wi is the molecular mass of species i.

7 Model Setup

In order to ease the setup of models employing the CHEMKIN interface, a SATLIT code, CHEMST, and two PIL fragments have been supplied. Prior to calling CHEMST the user should, where appropriate:

set the value of CSG4, to identify LINK files with non-default names
set the value of CHSOB, the index of the 1st CHEMKIN variable
set the value of CHSOA, to determine the solution algorithm
issue the commands STORE(TEM1) or SOLVE(TEM1)
set the variable CHSOA (=GRND9 to use the implicit PBP solver)
set any CHEMK source PATCHes needed

When called, the routine CHEMST does the following:

it reads the CHEMKIN appropriate CHEMKIN link file (CKLINK, or xxxxckln)
it sets up dependent variables for the CHEMKIN species
it sets COVALs for any CHEMK source PATCHes
it sets VARMIN and VARMAX values for species and, if appropriate, for the temperature
if the implicit PBP solver is selected, it makes settings of RESREF and ENDIT values that are roughly appropriate
it returns the number of species in the CHEMKIN scheme in the variable CHSOD
it returns the finallised location of the first CHEMKIN variable in the variable CHSOB

9 Developments and modifications

9.1 Developments
9.2 Modifications Made to CHEMKIN Routines

9.1 Developments

There are a number of areas in which work remains to be done, and these are:-

Turbulent combustion - nothing has been done because the modelling of turbulent combustion is still poorly understood and so it is not clear which model should be adopted or how useful such a model would be;
Modified diffusion terms - these are incomplete for BFC cases with appreciable non-orthogonality;
Surface chemistry - nothing explicit has been, though the existing gas-phase chemistry can be used to model surface chemistry in an approximate fashion;

Much more can be done in many areas, but what should be done depends upon the demand for further deveopments.

9.2 Modifications Made to CHEMKIN Routines

No modifications have been made to any subroutines in the CHEMKIN or TRANLIB libraries. The only software associated with CHEMKIN to be have been modified is the TWOPNT solver. The modifications made are:

the subroutine NORM has been renamed TPNORM in order to avoid a clash with a subroutine NORM within PHOENICS;
a section to access the PHOENICS clock has been added to the subroutine CPUTIM.

10. Sources of Further Information

Further information can be found in the references cited below, and a lecture is provided under the POLIS entries: 'Lectures on PHOENICS', 'Turbulence and Combustion'. Additional information on running CHEMKIN can be found under the POLIS entries 'About PHOENICS 2.2', 'How to run PHOENICS modules'.

R.J.Kee, F.M.Rupley, J.A.Miller, 'CHEMKIN-II: A FORTRAN Chemical Kinetics Package for the Analysis of Gas-Phase Chemical Kinetics', SAND89-8009B, UC-706, Sandia National Laboratories, Albuquerque, New Mexico, (1993a).
R.J.Kee, G.Dixon-Lewis, J.Warnatz, M.E.Coltrin, and J.A.Miller, 'A FORTRAN Computer Code for the Evaluation of Gas-Phase Multicomponent Transport Properties", Sandia Report SAND86-8246, UC-401, (1993b).
R.J.Kee, F.M.Rupley and J.A.Miller, 'The CHEMKIN Thermodynamic Data Base', Sandia Report SAND87-8215B, UC-4, (1993c).
P.Glarborg, R.J.Kee, J.F.Grear, J.A.Miller,'PSR: A FORTRAN Program for Modelling Well-Stirred Reactors', SAND86-8209, Sandia National Laboratories, Albuquerque, New Mexico, (1992).
J.F.Grear, 'The Twopnt Program for Boundary Value Problems', Sandia Report SAND91-8230, (1992)