Chemkin format uses NASA-7 polynomials in the form C_p / R = a_1 + a_2 T + a_3 T^2 + a_4 T^3 + a_5 T^4 (see e.g. NASA Polynomials or CHEMKIN Data and NASA Polynomials).
Should the related formula in Species definitions — MFIX-Exa documentation be c_p(T) / R = \sum_{i=0}^4 a_i T^i ? (Note division by R and the upper bound on the sum.)
John,
thanks for your observation.
Yes, the related formula in the documentation needs to be corrected.
I have a fix ready to be merged, and soon you should see the documentation updated with the correct definition of the specific heat coefficients.
Roberto
Thanks @RobertoPorcu !
Related: I don’t see a place where the sixth coefficient is used, but it is required nonetheless. Did I overlook something, is this part of future plans, or should this not be a required input?
You’re correct,
The sixth coefficient was left in there as part of future plans.
Related request: Could you also clarify for future users that constant heat capacities are per unit mass, not per mol, assuming this is indeed the case?
See equations 2-71, 2-72 and 2-73 in CHEMKIN Data and NASA Polynomials The 6th and 7th coefficients are used to calculate enthalpy and entropy, but not specific heat