Title: A forward tracking scheme for solving radionuclide advective problems in unsaturated porous media

Authors: J. Aquino, F. Pereira, H.P. Amaral Souto, A.S. Francisco

Addresses: Departamento de Modelagem Computacional, Instituto Politecnico, Universidade do Estado do Rio de Janeiro, Caixa Postal 97282, 28601–970 Nova Friburgo, RJ, Brazil. ' Departamento de Modelagem Computacional, Instituto Politecnico, Universidade do Estado do Rio de Janeiro, Caixa Postal 97282, 28601–970 Nova Friburgo, RJ, Brazil. ' Departamento de Modelagem Computacional, Instituto Politecnico, Universidade do Estado do Rio de Janeiro, Caixa Postal 97282, 28601–970 Nova Friburgo, RJ, Brazil. ' Departamento de Ciencia dos Materiais, Escola de Engenharia Industrial Metalurgica de Volta Redonda, Universidade Federal Fluminense, Av. dos Trabalhadores, 420, 27255–250 Volta Redonda, RJ, Brazil

Abstract: In this paper we consider the numerical approximation of the problem of radionuclide contaminant transport in unsaturated porous media. The problem is modelled by a system of equations that describes the two-phase water–air flow and the radionuclide transport. We solve numerically the water–air flow equations combining mixed finite elements with a non-oscillatory central finite difference scheme. For the numerical approximation of the advective transport of the radionuclide, we introduce the Forward Integral-Tube Tracking (FIT) scheme, which is locally mass conservative and virtually free of numerical diffusion. Moreover, large time steps can be used without loss of accuracy in the numerical solution. We perform numerical experiments to compare the Locally Conservative Eulerian-Lagrangian Method (LCELM) and the FIT scheme; our results show that the FIT scheme produces more accurate results.

Keywords: two-phase flow; locally conservative Lagrangian method; radionuclide transport; unsaturated porous medium; nuclear technology; nuclear power; nuclear energy; modelling; water–air flow; advective transport; finite element method; FEM; finite difference; radionuclide contaminant; forward tracking.

DOI: 10.1504/IJNEST.2007.014656

International Journal of Nuclear Energy Science and Technology, 2007 Vol.3 No.2, pp.196 - 205

Available online: 23 Jul 2007 *

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