Publications

Safta, Cosmin S.; Najm, H.N.; Diaz-Ibarra, Oscar H.; Kim, Kyungjoo K.

The TChem open-source software is a toolkit for computing thermodynamic properties, source term, and source term’s Jacobian matrix for chemical kinetic models that involve gas and surface reactions.

Diaz-Ibarra, Oscar H.; Kim, Kyungjoo K.; Safta, Cosmin S.; Najm, H.N.

CSPlib is an open source software library for analyzing general ordinary differential equation (ODE) systems and detailed chemical kinetic ODE/DAE systems. It relies on the computational singular perturbation (CSP) method for the analysis of these systems.

Najm, H.N.; Sargsyan, Khachik S.; Kim, Kyungjoo K.; Goldsmith, C.F.; West, Richard H.; Bylaska, Eric J.; Bross, David H.; Ruscic, Branko R.; Safta, Cosmin S.; Zador, Judit Z.; Blais, Christopher B.; Blöndal, Katrín B.; Diaz-Ibarra, Oscar H.; Hermes, Eric H.; Mazeau, Emily J.

Abstract not provided.

Christopher, Blais C.; Diaz-Ibarra, Oscar H.; Mazeau, Emily J.; Gierada, Maciej G.; Hermes, Eric H.; Safta, Cosmin S.; Kim, Kyungjoo K.; Najm, H.N.; Bylaska, Eric J.; Zador, Judit Z.; Goldsmith, C.F.; West, Richard H.

Abstract not provided.

Safta, Cosmin S.; Diaz-Ibarra, Oscar H.; Kim, Kyungjoo K.; Najm, H.N.

Abstract not provided.

Safta, Cosmin S.; Diaz-Ibarra, Oscar H.; Najm, H.N.; Kim, Kyungjoo K.

Abstract not provided.

Combustion Theory and Modelling

Diaz-Ibarra, Oscar H.; Kim, Kyungjoo K.; Safta, Cosmin S.; Zador, Judit Z.; Najm, H.N.

We have extended the computational singular perturbation (CSP) method to differential algebraic equation (DAE) systems and demonstrated its application in a heterogeneous-catalysis problem. The extended method obtains the CSP basis vectors for DAEs from a reduced Jacobian matrix that takes the algebraic constraints into account. We use a canonical problem in heterogeneous catalysis, the transient continuous stirred tank reactor (T-CSTR), for illustration. The T-CSTR problem is modelled fundamentally as an ordinary differential equation (ODE) system, but it can be transformed to a DAE system if one approximates typically fast surface processes using algebraic constraints for the surface species. We demonstrate the application of CSP analysis for both ODE and DAE constructions of a T-CSTR problem, illustrating the dynamical response of the system in each case. We also highlight the utility of the analysis in commenting on the quality of any particular DAE approximation built using the quasi-steady state approximation (QSSA), relative to the ODE reference case.

Diaz-Ibarra, Oscar H.; Kim, Kyungjoo K.; Safta, Cosmin S.; Najm, H.N.

CSPlib is an open source software library for analyzing general ordinary differential equation (ODE) systems and detailed chemical kinetic ODE systems. It relies on the computational singular perturbation (CSP) method for the analysis of these systems. The software provides support for: General ODE models (gODE model class) for computing source terms and Jacobians for a generic ODE system; TChem model (ChemElemODETChem model class) for computing source term, Jacobian, other necessary chemical reaction data, as well as the rates of progress for a homogenous batch reactor using an elementary step detailed chemical kinetic reaction mechanism. This class relies on the TChem [2] library; A set of functions to compute essential elements of CSP analysis (Kernel class). This includes computations of the eigensolution of the Jacobian matrix, CSP basis vectors and co-vectors, time scales (reciprocals of the magnitudes of the Jacobian eigenvalues), mode amplitudes, CSP pointers, and the number of exhausted modes. This class relies on the Tines library; A set of functions to compute the eigensolution of the Jacobian matrix using Tines library GPU eigensolver; A set of functions to compute CSP indices (Index Class). This includes participation indices and both slow and fast importance indices.