Abstract
Modelling long-time convective flows in the interiors of stars is extremely challenging using conventional compressible hydrodynamics codes due to the acoustic timestep limitation. Many of these flows are in the low Mach number regime, which allows us to exploit the relationship between acoustic and advective time scales to develop a more computationally efficient approach. MAESTROeX is an open source low Mach number stellar hydrodynamics code that allows much larger timesteps to be taken, therefore enabling systems to be modelled for much longer periods of time. This is particularly important for the problem of convection in the cores of rotating massive stars prior to core collapse. To fully capture the dynamics, it is necessary to model these systems in three dimensions at high resolution over many rotational periods. We present an overview of MAESTROeX’s current capabilities, describe ongoing work to incorporate the effects of rotation and discuss how we are optimising the code to run on GPUs.
Highlights
For many flows in astrophysical systems, the magnitude of the fluid velocity is much less than the soundspeed
Our work porting MAESTROeX to run on GPUs is still ongoing, in Figure 1 we show the speedup we have achieved so far for a number of individual functions that have been offloaded to GPU
MAESTROeX is a new and improved version of our previous code Maestro. It is based on AMReX, which allows us to exploit its powerful new solvers and make use of ongoing improvements
Summary
For many flows in astrophysical systems, the magnitude of the fluid velocity is much less than the soundspeed. The technique that we use in MAESTROeX is to modify the fluid equations themselves so as to filter out the soundwaves This is a similar approach to the incompressible [8] and anelastic [9,10,11] approximations, the approximation that we use (called the low Mach number approximation [12,13,14] and the generalised pseudo-incompressible approximation [15]) allows for background stratification and large density and temperature perturbations due to heating and changes in composition.
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