WIAS Preprint No. 48, (1993)

Finite element approximation of transport of reactive solutes in porous media. Part I: Error estimates for non-equilibrium adsorption processes.


Authors

  • Barrett, John W.
  • Knabner, Peter

2010 Mathematics Subject Classification

  • 65M15 65M60 35K65 35R35 35K55 76S05

Keywords

  • Finite element approximation, error estimates, degenerate parabolic equation, energy norm estimates, flow in porous media

DOI

10.20347/WIAS.PREPRINT.48

Abstract

In this paper we analyse a fully practical piecewise linear finite element approximation; involving regularization, numerical integration and backward Euler time discretisation; of the following degenerate parabolic system arising in a model of reactive solute transport in porous media: Find {u(x,t),v(x,t)} such that

∂tu + ∂tv - Δu = f in Ω x (0,T] u=0 on ∂ Ω x (0,T]

∂tv = k (φ(u)-v) in Ω x (0,T]

u(•,0) = g1 (•) v(•,0) = g 2 (•) in Ω ⊂ ℝd, 1 ≤ d ≤ 3

for given data k ∈ + ℝ+, f, g1, g2 and a monotonically increasing φ ∈ C0 (ℝ) ∩C1(-∞,0]∪(0,∞) satisfying φ(0) = 0; which is only locally Hölder continuous, with exponent p ∈ (0,1), at the origin; e.g. φ (s) ≡ [s]p+. This lack of Lipschitz continuity at the origin limits the regularity of the unique solution {u,v} and leads to difficulties in the finite element error analysis. Nevertheless we arrive at error bounds which in some cases exhibit the full approximation power of the trial space.

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