James Jackaman

Norwegian University of Technology and Science · Department of Mathematical Sciences

A key consideration in the development of numerical schemes for time-dependent partial differential equations (PDEs) is the ability to preserve certain properties of the continuum solution, such as associated conservation laws or other geometric structures of the solution. There is a long history of the development and analysis of such structure-pr...

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We propose a novel algorithmic method for constructing invariant variational schemes of systems of ordinary differential equations that are the Euler–Lagrange equations of a variational principle. The method is based on the invariantization of standard, noninvariant discrete Lagrangian functionals using equivariant moving frames. The invariant vari...

An energy conservative discontinuous Galerkin scheme for a generalised third order KdV type equation is designed. Based on the conservation principle, we propose techniques that allow for the derivation of optimal a priori bounds for the linear KdV equation and a posteriori bounds for the linear and modified KdV equation. Extensive numerical experi...

We propose a novel algorithmic method for constructing invariant variational schemes of systems of ordinary differential equations that are the Euler-Lagrange equations of a variational principle. The method is based on the invariantization of standard, non-invariant discrete Lagrangian functionals using equivariant moving frames. The invariant var...

In this work we propose a new, arbitrary order space-time finite element discretisation for Hamiltonian PDEs in multisymplectic formulation. We show that the new method which is obtained by using both continuous and discontinuous discretisations in space, admits a local and global conservation law of energy. We also show existence and uniqueness of...

In this work we propose a new, arbitrary order space-time finite element discretisation for Hamiltonian PDEs in multi-symplectic formulation. We show that the new method which is obtained by using both continuous and discontinuous discretisations in space, admits local and global conservation laws of energy and momentum. We show existence and uniqu...

In this paper we introduce a procedure, based on the method of equivariant moving frames, for formulating continuous Galerkin finite element schemes that preserve the Lie point symmetries of initial value ordinary differential equations. Our methodology applies to projectable and non-projectable actions for ordinary differential equations of arbitr...

In this work we design a conservative discontinuous Galerkin scheme for a generalised third order KdV type equation. The techniques we use allow for the derivation of optimal a priori and a posteriori bounds. We summarise numerical experiments showcasing the good long time behaviour of the scheme.

In this note we examine the a priori and a posteriori analysis of discontinuous Galerkin finite element discretisations of semilinear elliptic PDEs with polynomial nonlinearity. We show that optimal a priori error bounds in the energy norm are only possible for low order elements using classical a priori error analysis techniques. We make use of ap...

We design a consistent Galerkin scheme for the approximation of the vectorial modified Korteweg-de Vries equation. We demonstrate that the scheme conserves energy up to machine precision. In this sense the method is consistent with the energy balance of the continuous system. This energy balance ensures there is no numerical dissipation allowing fo...