Numerical Methods for Reacting Gas Flow Simulations

In this study various numerical schemes for simulating 2D laminar reacting gas flows, as typically found in Chemical Vapor Deposition (CVD) reactors, are proposed and compared. These CVD systems are generally modeled by means of many stiffly coupled elementary gas phase reactions between a large number of reactants and intermediate species. The purpose of this study is to develop robust and efficient solvers for the stiff heat-reaction system, whereby the velocities are assumed to be given. For non-stationary CVD simulation, an optimal combination in terms of efficiency and robustness between time integration, nonlinear solvers and linear solvers has to be found. Besides stability, which is important due to the stiffness of the problem, the preservation of non-negativity of the species is crucial. It appears that this extra condition on time integration methods is much more restrictive towards the time-step than stability. For a set of suitable time integration methods necessary conditions are represented. We conclude with a comparison of the workload between the selected time integration methods. This comparison has been done for a 2D test problem. The test problem does not represent a practical process, but represents only the computational problems.