Document Type

Article

Publication Date

7-1-2006

Publication Title

Discrete and Continuous Dynamical Systems-Series B

Abstract

An equation that arises in mathematical studies of the transport of pollutants in groundwater and of oil recovery processes is of the form: -del x . (kappa(x,.)del(x)u(x, omega)) = f(x), for x is an element of D, where kappa(x,.), the permeability tensor, is random and models the properties of the rocks, which are not know with certainty. Further, geostatistical models assume kappa(x, .) to be a log-normal random field. The use of Monte Carlo methods to approximate the expected value of u(x,.), higher moments, or other functionals of u(x,.), require solving similar system of equations many times as trajectories are considered, thus it becomes expensive and impractical. In this paper, we present and explain several advantages of using the White Noise probability space as a natural framework for this problem. Applying properly and timely the Wiener-Ito Chaos decomposition and an eigenspace decomposition, we obtain a symmetric positive definite linear system of equations whose solutions are the coefficients of a Galerkin-type approximation to the solution of the original equation. Moreover, this approach reduces the simulation of the approximation to u(x,omega) for a fixed omega, to the simulation of a finite number of independent normally distributed random variables.

Volume

6

Issue

4

First Page Number

941

Last Page Number

955

Included in

Mathematics Commons

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