http://arxiv.org/abs/1901.06385
Explicit radiation hydrodynamic simulations of the atmospheres of massive stars and of convection in accretion discs around white dwarfs suffer from prohibitively short time steps due to radiation. This constraint is related to the cooling time rather than the radiative pressure. We show that the radiative time step constraint is governed by the minimum of the sum of the optically thick and thin contributions rather than the smaller of the two. In simulations with the Pencil Code, their weighting fractions are found to be about 0.2 and 4.2, respectively. In three-dimensional convective accretion disk simulations, the Deardorff term is found to be the main contributor to the enthalpy flux. We conclude with a discussion of how to mitigate the radiative time step problem.
A. Brandenburg and U. Das
Wed, 23 Jan 19
57/111
Comments: 22 pages, 9 figures, 3 tables, submitted to GAFD, special issue “Physics and Algorithms of the Pencil Code”
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