Akhlaq Husain
Articles written in Proceedings – Mathematical Sciences
Volume 125 Issue 2 May 2015 pp 239-270
P Dutt Akhlaq Husain A S Vasudeva Murthy C S Upadhyay
This is the first of a series of papers devoted to the study of ℎ- 𝑝 spectral element methods for solving three dimensional elliptic boundary value problems on non-smooth domains using parallel computers. In three dimensions there are three different types of singularities namely; the vertex, the edge and the vertex-edge singularities. In addition, the solution is anisotropic in the neighbourhoods of the edges and vertex-edges. To overcome the singularities which arise in the neighbourhoods of vertices, vertex-edges and edges, we use local systems of coordinates. These local coordinates are modified versions of spherical and cylindrical coordinate systems in their respective neighbourhoods. Away from these neighbourhoods standard Cartesian coordinates are used. In each of these neighbourhoods we use a geometrical mesh which becomes finer near the corners and edges. The geometrical mesh becomes a quasi-uniform mesh in the new system of coordinates. We then derive differentiability estimates in these new set of variables and state our main stability estimate theorem using a non-conforming ℎ- 𝑝 spectral element method whose proof is given in a separate paper.
Volume 125 Issue 3 August 2015 pp 413-447
P Dutt Akhlaq Husain A S Vasudeva Murthy C S Upadhyay
This is the second of a series of papers devoted to the study of $h-p$ spectral element methods for three dimensional elliptic problems on non-smooth domains. The present paper addresses the proof of the main stability theorem.We assume that the differential operator is a strongly elliptic operator which satisfies Lax–Milgram conditions. The spectral element functions are non-conforming. The stability estimate theorem of this paper will be used to design a numerical scheme which give exponentially accurate solutions to three dimensional elliptic problems on non-smooth domains and can be easily implemented on parallel computers.
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