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Displaying 461 –
480 of
601
In this short note we provide an optimal analysis of finite element convergence on meshes containing a so-called band of caps. These structures consist of a zig-zag arrangement of ‘degenerating’ triangles which violate the maximum angle condition. A necessary condition on the geometry of such a structure for various -convergence rates was previously given by Kučera. Here we prove that the condition is also sufficient, providing an optimal analysis of this special case of meshes. In the special...
We consider a finite element discretization by
the Taylor–Hood element for the stationary
Stokes and Navier–Stokes
equations with slip boundary condition. The slip boundary condition
is enforced pointwise for nodal values of the velocity in
boundary nodes. We prove optimal error estimates in the
H1 and L2 norms for the velocity and pressure respectively.
We consider the analysis and
numerical solution of a forward-backward boundary value problem.
We provide some motivation, prove existence and uniqueness in a function
class especially geared to the problem at hand, provide various energy
estimates, prove a priori error estimates for the Galerkin method,
and show the results of some numerical computations.
A second order elliptic problem with axisymmetric data is solved in a finite element space, constructed on a triangulation with curved triangles, in such a way, that the (nonhomogeneous) boundary condition is fulfilled in the sense of a penalty. On the basis of two approximate solutions, extrapolates for both the solution and the boundary flux are defined. Some a priori error estimates are derived, provided the exact solution is regular enough. The paper extends some of the results of J.T. King...
We are concerned with a finite element approximation for time-harmonic wave
propagation governed by the Helmholtz equation. The usually oscillatory behavior of
solutions, along with numerical dispersion, render standard finite element methods
grossly inefficient already in medium-frequency regimes. As an alternative, methods
that incorporate information about the solution in the form of plane waves have
been proposed. We focus on a class of Trefftz-type discontinuous Galerkin methods that
...
In this paper, we study a postprocessing procedure for improving
accuracy of the finite volume element approximations of semilinear
parabolic problems. The procedure amounts to solve a source problem
on a coarser grid and then solve a linear elliptic problem on a
finer grid after the time evolution is finished. We derive error
estimates in the L2 and H1 norms for the standard finite
volume element scheme and an improved error estimate in the H1
norm. Numerical results demonstrate the accuracy...
One of the main tools in the proof of residual-based a posteriori error
estimates is a quasi-interpolation operator due to Clément.
We modify this operator in the setting of a partition of unity
with the effect that the approximation error has a local average zero.
This results in a new residual-based a posteriori error estimate
with a volume contribution which is smaller than in the standard estimate.
For an elliptic model problem, we discuss applications to conforming,
nonconforming and mixed...
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