Aplicação do método de complementaridade não linear para o estudo de combustão de oxigênio in situ

Abstract

Some parabolic problems can be rewritten in complementarity form and appear in many applications such as liquid flows within a domain, diffusion, heat flow involving phase change and chemical reactions. These types of problems have many analytical and numerical difficulties, usually due to the evolution in time or moving boundary. Since the analytical solution is very difficult to obtain, so it is important to study numerical methods that allow the search for an approximate solution of the exact solution for these types of problems. We study the conservation laws and the types of solutions associated with the Riemann Problem, these types of laws are essentially balance laws that express the fact that some substance is balanced. The study of this theory is important because the conservation laws often appear when the parabolic problems are neglected the diffusive terms of second order. It also presents a numerical method which is a variation of the Newton’s method for solving nonlinear systems, the method is based on an implicit finite difference scheme and an algorithm complementary non-linear FDA–NCP. The given method has the advantage of providing a global convergence with respect to the finite difference method with Newton’s method which has only local convergence. The theory is applied to the model difussion in tissue of oxygen and oxygen combustion model in situ, this two models are linear and nonlinear parabolics problems respectively and which can be rewritten in the form of complementarity problem. The first model that can be applied in the treatment of cancer cells leads to a free boundary problem, while the second model, consider a one-dimensional process of air injection inside a porous medium initially containing solid fuel and where combustion occurs gas - solid thus the model involves the heat balance law, law and the fuel molar ideal gas law, in addition, studies the thermal wave and the wave associated fuel.