The Solution of Very Large Non-Linear Algebraic Systems

The manuscript describes how to simulate the formation of macro and micropollutants in complex combustion devices. This is not possible by simply introducing a detailed kinetic scheme into a fluid dynamics (CFD) code. Actually, the resulting problem would reach a so huge dimension that is still orders of magnitude larger than the feasible one (by means of modern computing devices). To overcome this obstacle it is possible to implement a separate and dedicated kinetic post-processor (KPP) that, starting from the CFD output data, allows simulating the combustion in a burner by means of a detailed kinetic scheme. The resulting numerical problem consists of the solution of a very large algebraicnon-linear system comprising a few millions of variables. The manuscript describes the KPP organization and structure as well as the numerical challenges and difficulties that must be overcome to get the final numerical solution.