Integrating factors and the compression of gas-phase reaction mechanisms

Integrating factors have been used to temporarily compress the differential equations describing the rates of change of the species of a gas-phase reaction mechanism, resulting in a faster simulation of gas-phase chemistry. The processing time requirements have been reduced by up to a factor of 3.7, by combining the use of Bernoulli’s integrating factors with the assumption of linear time dependence within each substep of a multistep integration. No formal loss in accuracy relative to the original system was observed, with a suite of 2511 test cases having average errors of the same magnitude as the iteration error allowed within the numerical solver. The method thus presents a significant means for reducing the simulation time required by atmospheric reaction-transport models. Crown Copyright