The multi-species data such as reaction rate constants, specific heats, atomic data etc can be supplied to USim using a separate file. Each of the data sets have to be written in USim specific data format into separate blocks.
data of all properties are enclosed between ‘PROPERTY START’ and ‘PROPERTY END’ lines. The data format changes for different properties. Following are the properties currently accepted by USim data file.
REACTIONS chemical reactions
CP specific heat at constant pressure
EOF standard energy of formation
MOLECULARWEIGHT molecular weight
MOLECULARDIA molecular diameter
DOF degrees of freedom of a gas molecule
The data block format is explained referring to the example given below. Block header REACTIONS START is followed by list of species SPECIES N2 N O2 O NO. Five species are given in this example. Each of the species is delimited by space. The data corresponding to the rate constants of each of the reactions follows. Each of the reactions should be entered in a separate line. Three reactions are given in this example. The data block ends with REACTIONS END line. Three types of rate constants can be specified. The data formats of change according to the type of rate constant. These three rate constant types are used in the three reactions of the example.
Reaction-1 \(N_2 + O_2 \rightleftharpoons 2NO\). Fixed rate constant type F is specified as input.
Forward rate constant \(k_{f} = 10^{-8}\) fixed value
Back Ward rate constant \(k_{b} = 0.0\) fixed value
‘Number-of-species-on-LHS’ ‘Number-of-species-on-RHS’ ‘fixed-rate-constant’ ‘forward-rate-constant’ ‘backward-rate-constant’ ‘LHS-species-followed-by-RHS-species’
Reaction-2 \(N + O_2 \rightleftharpoons NO + O\). Arrhenius rate constant type A is specified as input.
Forward rate constant \(k_{f} = A \left(\frac{T}{298} \right)^n e^{\left(\frac{-Ea}{RT}\right)}\)
Back Ward rate constant \(k_{b} = A \left(\frac{T}{298} \right)^n e^{\left(\frac{-Ea}{RT}\right)}\)
‘Number-of-species-on-LHS’ ‘Number-of-species-on-RHS’ ‘Arrhenius-rate-constant’ ‘Temperature-range-lower-limit’ ‘Temperature-range-upper-limit’ ‘Arrhenius-forward-rate-constant-coefficients A n Ea’ ‘Arrhenius-backward-rate-constant-coefficients A n Ea’ ‘LHS-species-followed-by-RHS-species’
Reaction-3 \(N_2 + O \rightleftharpoons NO + N\). Arrhenius and equilibrium rate constant type E is specified as input.
Forward rate constant \(k_{f} = A \left(\frac{T}{298} \right)^n e^{\left(\frac{-Ea}{RT}\right)}\)
Equilibrium rate constant \(k_{e} = B e^{\left(\sum\limits_{i=0}^m c_{i}\left(\frac{10000}{T}\right)^i\right)}\)
Backward rate constant \(k_{b} = k_{f}/k_{e}\)
‘Number-of-species-on-LHS’ ‘Number-of-species-on-RHS’ ‘Arrhenius-equilibrium-rate-constant’ ‘Temperature-range-lower-limit’ ‘Temperature-range-upper-limit’ ‘forward-rate-constant-coefficients A n Ea’ ‘equilibrium-rate-constant-coefficients B m c0 c1 .... cm’ ‘LHS-species-followed-by-RHS-species’
REACTIONS START
SPECIES N2 N O2 O NO
2 2 F 1.0E-8 0.0 N2 O2 NO NO
2 2 A 300.0 11000.0 6.43E-18 1.0E+0 3.16E+4 1.58E-8 1.0E+0 1.64E+5 N O2 NO O
2 2 E 300.0 12000.0 4.0E-9 0.0 0.0 2.0 5 0.0 0.0 0.0 0.0 0.0 N2 O NO N
REACTIONS END
The specific heat data block format is explained referring to the example given below. Block header ‘CP START’ is followed by list of species ‘SPECIES N2 N O2 O NO’. Five species are given in this example. Each of the species is delimited by space. The specific heat data of each of the species is entered in a separate line in the same order as that of the species list. The block ends with ‘CP END’ line.
Specific heat at constant pressure can be specified using Shomate polynomials defined in multiple temperature ranges \(C_p = a_0 + a_1 t + a_2 t^2 + a_3 t^3 + \frac{a_4}{t^2}\), where \(t = T/1000\).
\(C_{p,N_2}\) single polynomial is specified in the temperature range [100,500] K.
‘Number-of-polynomials’ ‘Temperature-range-lower-limit’ ‘Temperature-range-upper-limit’ ‘Number-coefficients-in-the-polynomial’ ‘polynomial1-coefficients’
\(C_{p,NO}\) two polynomials are specified in the temperature ranges [298,1200] and (1200,6000] K.
‘Number-of-polynomials’ ‘Temperature-range-lower-limit1’ ‘Temperature-range-upper-limit1’ ‘Number-coefficients-in-the-polynomial1’ ‘polynomial1-coefficients’ ‘Temperature-range-lower-limit2’ ‘Temperature-range-upper-limit2’ ‘Number-coefficients-in-the-polynomial2’ ‘polynomial2-coefficients’
CP START
SPECIES N2 N O2 O NO
1 100.0 500.0 5 28.98641 1.853978 -9.647459 16.63537 0.000117
1 298.0 6000.0 5 21.13 -0.388 0.04 0.02 -0.025
3 100.0 700.0 5 31.32 -20.23 57.86 -36.50 -0.0073 700.0 2000.0 5 30.0 8.77 -3.988 0.788 -0.7415 2000.0 6000.0 5 20.91 10.72 -2.02 0.14 9.2
1 298.0 6000.0 5 21.13 -0.388 0.04 0.02 -0.025
2 298.0 1200.0 5 23.83 12.58 -1.139 -1.497 0.214 1200.0 6000.0 5 35.99 0.95 -0.148 0.0099 -3.0
CP END
Each of the above mentioned properties are constant and hence share the same block format with the corresponding starting and ending lines. The example below is for molecular weight data. Block header ‘MOLECULARWEIGHT START’ is followed by list of species ‘SPECIES N2 N O2 O NO’. Each of the species is delimited by space. The next line has the molecular weights entered in the same order as that of the species list. The block is closed with ‘MOLECULARWEIGHT END’.
MOLECULARWEIGHT START
SPECIES N2 N O2 O NO
28.0 14.0 32.0 16.0 30.0
MOLECULARWEIGHT END