Solving reduced chemical models in air pollution modelling

Abstract

This article follows [R. Djouad, B. Sportisse, Appl. Numer. Math. 43 (2002) 383] in which we have proposed an automatic method in order to generate reduced atmospheric chemical mechanisms. On the basis of the slow/fast behaviour of chemical kinetics the exact model is replaced by a differential–algebraic system. We propose here an easy to perform algorithm in order to integrate such systems with a low CPU cost. Comparison is made with some classical solvers such as Euler Backward Implicit (EBI), QSSA and the second-order Rosenbrock method ROS2. This proves the efficiency and the accuracy of the proposed algorithm. We also show that the classical QSSA-like methods cannot be used apart from the framework of reduction procedures, which explains their rather poor accuracy.