AUDIT , Edouard

We derive a simple method to numerically approximate the solution of the two-dimensional Riemann problem for gas dynamics, using the literal extension of the well-known HLL formalism as its basis. Essentially, any strategy attempting to extend the three-state HLL Riemann solver to multiple space dimensions will by some means involve a piecewise...

We report on our study aimed at deriving a simple method to numerically approximate the solution of the two-dimensional Riemann problem for gas dynamics, using the literal extension of the well-known HLL formalism as its basis. Essentially, any strategy attempting to extend the three-state HLL Riemann solver to multiple space dimensions will by...

Many astrophysical flows are modeled by the Euler equations with gravity source terms derived from a potential, the evolution of which is described by a Poisson equation. Several gravitational flows reach equilibrium states that are necessary to preserve in the numerical formulation. In this paper, we present the derivation of the relaxation...

Numerical simulations of the magnetohydrodynamics (MHD) equations have played a significant role in plasma research over the years. The need of obtaining physical and stable solutions to these equations has led to the development of several schemes, all requiring to satisfy and preserve the divergence constraint of the magnetic field...

We study the Euler equations with gravitational source terms derived from a potential which satisfies Poisson's equation for gravity. An adequate treatment of the source terms is achieved by introducing their discretization into an approximate Riemann solver, relying on a relaxation strategy. The associated numerical scheme is then presented...

We present a new numerical method to approximate the solutions of an Euler-Poisson model, which is inherent to astrophysical flows where gravity plays an important role. We propose a discretization of gravity which ensures adequate coupling of the Poisson and Euler equations, paying particular attention to the gravity source term involved in...

Using radiation hydrodynamics and radiative transfer simulations, we explore the origin of the spectral diversity of interacting supernovae (SNe) of Type IIn. We revisit SN 1994W and investigate the dynamical configurations that can give rise to spectra with narrow lines at all times. We find that a standard ∼10 M$_\odot$ 10$^{51}$ erg SN...

Just as the quality of a one-dimensional approximate Riemann solver is improved by the inclusion of internal sub-structure, the quality of a multidimensional Riemann solver is also similarly improved. Such multidimensional Riemann problems arise when multiple states come together at the vertex of a mesh. The interaction of the resulting...