Wednesday, April 2, 2008 : 9:20 a.m.
Coupling of Probabilistic Cellular Automata and a Stochastic Algorithm for Reactive Transport Simulation in Porous Media
The pollution of groundwater has been growing increasingly due to industrial development. Identification of the proper remedial measures depends on the detailed study on transport and reaction mechanisms in ground water systems. Due to this, efficient simulation models are necessary which are capable of representing a multitude of parameters that influence geochemical reactions. Reactive transport models couple mass transfer processes, abiotic transformations and microbial activities with transport processes such as advection and dispersion. The quantitative description of all these subsurface processes limits the practical application of models. The mathematical structure of the problem is determined by the decision in the chemical model part. If the reactions are kinetically controlled, then linear partial differential equations (PDEs) of the transport step have to be coupled with a non-linear system of ordinary differential equations (ODEs).The Operator Splitting (OS) or Time Splitting (TS) approach is a favorite and approved method for simulating multicomponent reactive transport systems. Operationally, this technique proceeds with a single time step in two stages, one comprehends the solution of the transport equation and the other involves in solving geochemical rate equations. This scheme can be easily adapted to the situation where large time scale differences between the transport and reaction steps exist. The OS enables us to take the advantage of applying different schemes suitable to the specific type of problem. In normal OS technique, the transport equation is solved by numerical techniques such as the finite difference, the finite element or the finite volume method. The solution of the reaction part is achieved with ordinary differential equation integrators. In this paper, different methods of coupling such as Finite Difference & Gillespie Algorithm (FD-GA) and Finite Difference & Ordinary Differential Equation (FD-ODE) are presented and results are analyzed.
Jegathambal Palanichamy, RWTH Aachen I am a post doctoral student
Torsten Becker, RWTH Aachen Research Engineer
Jürgen Köngeter, RWTH Aachen Head of IWW
Mohan Sankaralingam, IITM, Chennai He is the Professor and Head of Department of Civil Engineering