IMA Journal of Numerical Analysis Advance Access published online on March 30, 2009
IMA Journal of Numerical Analysis, doi:10.1093/imanum/drn044
A semi-Lagrangian–Galerkin projection scheme for convection equations


Departamento de Matemática Aplicada, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, C/ José Gutiérrez Abascal 2, 28006 Madrid, Spain
Corresponding author. Email: rbermejo{at}etsii.upm.es
Email: jaime.carpio{at}upm.es
Received on 20 July 2006. Revised on 6 May 2008.
| Abstract |
|---|
We introduce in this paper a semi-Lagrangian–Galerkin projection scheme to discretize backwards in time along the characteristics the convection terms of convection–diffusion equations. The scheme consists of a transport step in which the elements of the fixed mesh are transported backwards along the characteristic curves, thus generating a new mesh composed of curved elements, followed by an approximate L2-projection onto the finite-element space associated with the transported mesh. The new scheme is to some extent related to the so-called Lagrange–Galerkin (or characteristic-Galerkin) methods, but it may be more efficient because the number of trajectories per element to be calculated in the new scheme is smaller than that of the conventional characteristic-Galerkin scheme. It is also proved that, for linear convection problems with the velocity sufficiently smooth, the new scheme is unconditionally stable in the L2-norm and its order of convergence is
, where m is the degree of the polynomials of the finite-element space, and the velocity is in L
(0, T;Wq+1,
) with integer q
1.
Key Words: convection; characteristics; Lagrange–Galerkin; Galerkin projection; finite elements; semi-Lagrangian schemes