269 3 0430 2 0111 0 0444 8 0688 4 0441 2 0589 1

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Unformatted text preview: problem are displayed in Figure 1.3.4 for a uniform mesh with eight elements. It appears that the pointwise discretization errors are much smaller at nodes than they are globally. We'll see that this phenomena, called superconvergence, applies more generally than this single example would imply. Since nite element solutions are de ned as continuous functions (of x), we can also appraise their behavior in some global norms in addition to the discrete error norms used in Table 1.3.1. Many norms could provide useful information. One that we will use quite 18 Introduction 0.06 0.05 0.04 0.03 0.02 0.01 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure 1.3.4: Exact and piecewise-linear nite element solutions of Example 1.3.1 on an 8-element mesh. often is the square root of the strain energy of the error thus, using (1.3.2c) Z1 p kekA := A(e e) = p(e )2 + qe2 ]dx 0 0 1=2 : (1.3.23a) This expression may easily be evaluated as a summation over the elements in the spirit of (1.3.9a). With p = q = 1 for this exampl...
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This document was uploaded on 03/16/2014 for the course CSCI 6860 at Rensselaer Polytechnic Institute.

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