Orateur
Ann Almgren
(Lawrence Berkeley Lab, USA)
Description
Computational astrophysics has traditionally relied on discretizations of
either the fully compressible equations for fluid dynamics, or the
anelastic approximation, supplemented by equations describing the
thermonuclear reactions and heat release. The low Mach number formulation,
like the anelastic approximation, analytically removes acoustic wave propagation
from the system. However, the more general low Mach number approach
retains nonlinear compressibility effects resulting from nuclear burning,
compositional changes and changing radial stratification. This model
is a generalization of the pseudo-incompressible approximation
to systems with a non-ideal gas equation of state and a time-varying base state.
I will discuss the derivation of the low Mach number equation set for
astrophysics, focusing on the similarities with and differences from
numerical models of the Earth's atmosphere.
