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Displaying 281 –
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We show that the Maxwell equations in the low frequency limit, in a domain composed of insulating and conducting regions, has a saddle point structure, where the electric field in the insulating region is the Lagrange multiplier that enforces the curl-free constraint on the magnetic field. We propose a mixed finite element technique for solving this problem, and we show that, under mild regularity assumption on the data, Lagrange finite elements can be used as an alternative to edge elements.
We show that the Maxwell equations
in the low frequency limit, in a domain composed of insulating
and conducting regions, has a saddle point structure, where
the electric field in the insulating region is the Lagrange
multiplier that enforces the curl-free constraint on the magnetic field.
We propose a mixed finite element technique
for solving this problem, and we show that, under mild regularity
assumption on the data, Lagrange finite elements can be used
as an alternative to edge elements.
This paper deals with the mortar spectral element discretization of two equivalent problems, the Laplace equation and the
Darcy system, in a domain which corresponds to a nonhomogeneous anisotropic medium. The numerical analysis of the discretization
leads to optimal error estimates and the numerical experiments that we present enable us to verify its efficiency.
We consider the Laplace equation posed in a three-dimensional axisymmetric domain. We reduce the original problem by a Fourier expansion in the angular variable to a countable family of two-dimensional problems. We decompose the meridian domain, assumed polygonal, in a finite number of rectangles and we discretize by a spectral method. Then we describe the main features of the mortar method and use the algorithm Strang Fix to improve the accuracy of our discretization.
We consider the Laplace equation posed in a three-dimensional axisymmetric domain. We
reduce the original problem by a Fourier expansion in the angular variable to a countable
family of two-dimensional problems. We decompose the meridian domain, assumed polygonal,
in a finite number of rectangles and we discretize by a spectral method. Then we describe
the main features of the mortar method and use the algorithm Strang Fix to improve the
accuracy...
This paper presents a unified framework for the dual-weighted residual (DWR) method for a class of nonconforming FEM. Our approach is based on a modification of the dual problem and uses various ideas from literature which are combined in a new manner. The results are new error identities for some nonconforming FEM. Additionally, a posteriori error estimates with respect to the discrete -seminorm are derived.
It is well-known that the “standard” oblique derivative problem, in , on ( is the unit inner normal) has a unique solution even when the boundary condition is not assumed to hold on the entire boundary. When the boundary condition is modified to satisfy an obliqueness condition, the behavior at a single boundary point can change the uniqueness result. We give two simple examples to demonstrate what can happen.
We present an integral equation method for solving boundary value problems of the Helmholtz equation in unbounded domains. The method relies on the factorisation of one of the Calderón projectors by an operator approximating the exterior admittance (Dirichlet to Neumann) operator of the scattering obstacle. We show how the pseudo-differential calculus allows us to construct such approximations and that this yields integral equations without internal resonances and being well-conditioned at all frequencies....
We present an integral equation method for solving boundary value
problems of the Helmholtz equation in unbounded domains. The
method relies on the factorisation of one of the
Calderón projectors by an operator approximating the exterior
admittance (Dirichlet to Neumann) operator of the scattering
obstacle. We show how the pseudo-differential calculus allows us
to construct such approximations and that this yields integral
equations without internal resonances and being well-conditioned
at all...
The Method of Fundamental Solutions (MFS) is a boundary-type meshless method for the solution of certain elliptic boundary value problems. In this work, we investigate the properties of the matrices that arise when the MFS is applied to the Dirichlet problem for Laplace’s equation in a disk. In particular, we study the behaviour of the eigenvalues of these matrices and the cases in which they vanish. Based on this, we propose a modified efficient numerical algorithm for the solution of the problem...
The Method of Fundamental Solutions (MFS) is a boundary-type
meshless method for the solution of certain elliptic boundary
value problems. In this work, we investigate the properties of the
matrices that arise when the MFS is applied to the
Dirichlet problem for Laplace's equation in a disk. In particular,
we study the behaviour of the eigenvalues of these matrices and
the cases in which they vanish. Based on this, we propose a
modified efficient numerical algorithm for the solution of the
problem...
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