3 research outputs found
High-order residual distribution scheme for the time-dependent Euler equations of fluid dynamics
In the present work, a high order finite element type residual distribution
scheme is designed in the framework of multidimensional compressible Euler
equations of gas dynamics. The strengths of the proposed approximation rely on
the generic spatial discretization of the model equations using a continuous
finite element type approximation technique, while avoiding the solution of a
large linear system with a sparse mass matrix which would come along with any
standard ODE solver in a classical finite element approach to advance the
solution in time. In this work, we propose a new Residual Distribution (RD)
scheme, which provides an arbitrary explicit high order approximation of the
smooth solutions of the Euler equations both in space and time. The design of
the scheme via the coupling of the RD formulation \cite{mario,abg} with a
Deferred Correction (DeC) type method \cite{shu-dec,Minion2}, allows to have
the matrix associated to the update in time, which needs to be inverted, to be
diagonal. The use of Bernstein polynomials as shape functions, guarantees that
this diagonal matrix is invertible and ensures strict positivity of the
resulting diagonal matrix coefficients. This work is the extension of
\cite{enumath,Abgrall2017} to multidimensional systems. We have assessed our
method on several challenging benchmark problems for one- and two-dimensional
Euler equations and the scheme has proven to be robust and to achieve the
theoretically predicted high order of accuracy on smooth solutions
How to avoid mass matrix for linear hyperbolic problems
We are interested in the numerical solution of linear hyperbolic problems using continuous finite elements of arbitrary order. It is well known that this kind of methods, once the weak formulation has been written, leads to a system of ordinary differential equations in RN, where N is the number of degrees of freedom. The solution of the resulting ODE system involves the inversion of a sparse mass matrix that is not block diagonal. Here we show how to avoid this step, and what are the consequences of the choice of the finite element space. Numerical examples show the correctness of our approach