Adaptive Discontinuous Galerkin Methods for Non-linear by Murat Uzunca

By Murat Uzunca

The concentration of this monograph is the improvement of space-time adaptive ways to clear up the convection/reaction ruled non-stationary semi-linear advection diffusion response (ADR) equations with internal/boundary layers in a correct and effective manner. After introducing the ADR equations and discontinuous Galerkin discretization, strong residual-based a posteriori errors estimators in house and time are derived. The elliptic reconstruction process is then applied to derive the a posteriori mistakes bounds for the totally discrete procedure and to acquire optimum orders of convergence.As coupled floor and subsurface movement over huge house and time scales is defined by way of (ADR) equation the tools defined during this ebook are of excessive value in lots of components of Geosciences together with oil and gasoline restoration, groundwater illness and sustainable use of groundwater assets, storing greenhouse gases or radioactive waste within the subsurface.

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Extra resources for Adaptive Discontinuous Galerkin Methods for Non-linear Reactive Flows

Example text

Proof. 6) arising from the bilinear form ah (u, v) is positive definite. 4) produces a unique solution. 2 Adaptivity Advection dominated problems lead to internal/boundary layers where the solution has large gradients. The standard FEMs are known to produce strong oscillations around the layers. A naive approach is to refine the mesh uniformly. But it is not desirable as it highly increase the degree of freedom and refines the mesh unnecessarily in regions where the solutions are smooth. On the other hand, in the semi-linear ADR equations, in addition to the nonphysical oscillations due to the advection, non-linear reaction can be also responsible for sharp fronts.

2: Bisection of a triangle . , let ηK1 and ηK2 be the computed local error indicators corresponding to each unknown component of a two component system. Next, we determine the set of elements MK1 and MK2 satisfying ∑ K∈MK1 (ηK1 )2 ≥ θ ∑ (ηK1 )2 , K∈ξh ∑ K∈MK2 (ηK2 )2 ≥ θ ∑ (ηK2 )2 . K∈ξh Then, we refine the marked elements K ∈ MK1 ∪MK2 using the newest vertex bisection method. The adaptive procedure ends after a sequence of mesh refinements to attain a solution within a prescribed tolerance. 11) u · ∇wdx .

2 Adaptivity 39 1/2 ∑ T3 ηJ2K |||v|||, K∈ξh which completes the proof. 4. (Bound to the conforming part of the error) The conforming part of the error satisfies u − uch dG η +Θ . 31) Proof. Since u − uch ∈ H01 (Ω ), we have |u − uch |C = |β (u − uch )|∗ . 23), we get u − uch dG = |||u − uch ||| + |u − uch |C a˜h (u − uch , v) . |||v||| v∈H 1 (Ω )\{0} sup 0 So, we need to bound the term a˜h (u − uch , v). Using the fact that u − uch ∈ H01 (Ω ), we have a˜h (u − uch , v) = a˜h (u, v) − a˜h (uch , v) = = = Ω Ω Ω f vdx − bh (u, v) − a˜h (uch , v) f vdx − bh (u, v) − Dh (uch , v) − Jh (uch , v) − Oh (uch , v) f vdx − bh (uh , v) + bh (uh , v) − bh (u, v) − a˜h (uh , v) + Dh (urh , v) + Jh (urh , v) + Oh (urh , v).

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