IMA Journal of Numerical Analysis Advance Access originally published online on December 11, 2006
IMA Journal of Numerical Analysis 2007 27(4):741-764; doi:10.1093/imanum/drl036
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A posteriori estimates for approximations of time-dependent Stokes equations

Department of Mathematics, University of Crete, 71409 Heraklion, Crete, Greece

Department of Applied Mathematics, University of Crete, 71409 Heraklion, Crete, Greece and Institute of Applied and Computational Mathematics, FORTH, 71110 Heraklion Crete, Greece
Email: fotini{at}math.uoc.gr
Email: makr{at}tem.uoc.gr
Received on 16 September 2004. Revised on 3 April 2006.
| Abstract |
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In this paper, we derive a posteriori error estimates for space-discrete approximations of the time-dependent Stokes equations. By using an appropriate Stokes reconstruction operator, we are able to write an auxiliary error equation, in pointwise form, that satisfies the exact divergence-free condition. Thus, standard energy estimates from partial differential equation theory can be applied directly, and yield a posteriori estimates that rely on available corresponding estimates for the stationary Stokes equation. Estimates of optimal order in L
(L2) and L
(H1) for the velocity are derived for finite-element and finite-volume approximations.
Key Words: a posteriori error estimators; finite elements; finite volumes; time-dependent Stokes problem; discrete divergence-free spaces