By Repin, Sergey

This publication offers with the trustworthy verification of the accuracy of approximate suggestions that's one of many imperative difficulties in glossy utilized research. After giving an summary of the equipment built for versions according to partial differential equations, the writer derives computable a posteriori errors estimates by utilizing equipment of the speculation of partial differential equations and practical research. those estimates Read more...

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Additional info for A posteriori estimates for partial differential equations

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Peraire and A. T. Patera [260], E. Stein, M. R¨uter, and S. 6 A posteriori error indicators for finite element approximations 43 [340], and the literature cited in these publications). Aru rw f w/ dx D 0 8w 2 V0 WD HV 1 . 31) where A is a positive definite real matrix and and f 2 L2 . / is a given function. Let uh 2 V0 be an approximate solution computed on the mesh Th . Assume that it is required to estimate the quantity h`; u uh i, where ` 2 V0 is a given linear functional. Typically, ` is an integral type functional localized in a certain part of .

V u/k Ä krv qk; 8q 2 Qf : Take arbitrary y 2 L2 . /. 2. For any y 2 L2 . 7) inf ky q2Qf and for any y 2 H. ; div/, inf ky q2Qf Proof. Consider an auxiliary problem wf C f C div y D 0 wf D 0 in on ; where y 2 L2 . / and, therefore, f C div y 2 H 1 . 9) 8w 2 V0 ; which means that qN WD rwf C y 2 Qf . 10) . v u/k Ä krv yk C j div y C f j ; 8y 2 L2 . 11) However, the right-hand side of this estimate includes the norm j j , which is defined as the supremum over a functional space and, therefore, is not explicitly computable.

Adaptive methods for convection-diffusion problems are considered in C. Johnson [186] and R. Verf¨urth [360]. Papers by R. Verf¨urth [359] and K. Eriksson and C. Johnson [126] are devoted to parabolic type problems. A posteriori error estimates for anisotropic meshes are presented in K. G. Siebert [334] and G. Kunert [203, 204]. Also, we recommend papers by I. Babuˇska, R. Duran, and R. Rodriguez [25], G. F. Carey and D. L. Humphrey [84], J. T. Oden, L. Demkowicz, W. Rachowicz, and T. A. Westermann, [251], R.