Second order Implicit-Explicit Total Variation Diminishing schemes for the Euler system in the low Mach regime
This work addresses the need for stable and accurate numerical schemes for low Mach number flows, a known bottleneck in computational fluid dynamics.
The authors develop a new class of implicit-explicit TVD schemes for the compressible isentropic Euler system in the low Mach regime, achieving asymptotic stability with a CFL condition independent of Mach number and degenerating to a consistent incompressible discretization. The method interpolates between first and second order in space and time, preserving monotonicity and accuracy for all Mach numbers.
In this work, we consider the development of implicit explicit total variation diminishing (TVD) methods (also termed SSP: strong stability preserving) for the compressible isentropic Euler system in the low Mach number regime. The scheme proposed is asymptotically stable with a CFL condition independent from the Mach number and it degenerates in the low Mach number regime to a consistent discretization of the incompressible system. Since, it has been proved that implicit schemes of order higher than one cannot be TVD (SSP) \cite{GotShuTad}, we construct a new paradigm of implicit time integrators by coupling first order in time schemes with second order ones in the same spirit as highly accurate shock capturing TVD methods in space. For this particular class of schemes, the TVD property is first proved on a linear model advection equation and then extended to the isentropic Euler case. The result is a method which interpolates from the first to the second order both in space and time, which preserves the monotonicity of the solution, highly accurate for all choices of the Mach number and with a time step only restricted by the non stiff part of the system. In the last part, we show thanks to one and two dimensional test cases that the method indeed possesses the claimed properties.