Speaker
Prof.
Åke Nordlund
Description
We use the adaptive mesh refinement codes RAMSES and
DISPATCH to model protoplanetary disks in realistic star
formation environments, covering a range from a 40 pc outer
scale to an inner scale of 1/10 of an Earth radius (more than
12 orders of magnitude). The simulations are done in four
steps, with the first step following individual star formation in
a 40 pc GMC model with 120 AU resolution. In the 2nd step,
the neighborhoods of several stars with a final system mass
of 1-2 solar masses are followed during the accretion
process, with a smallest mesh size of 2 AU, sufficient to
follow the development of the large scale structure of the
accretion disks and their accretion histories. A selection of
these disks are then studied over 100-1000 yr, with mesh
sizes down to 0.015 AU. Using the new DISPATCH adaptive
mesh refinement code, we then study the dynamics of gas,
dust, and ensembles of chondrule size pebbles in the disk,
following the accretion of pebbles onto planetary embryos
surrounded by proto-atmospheres, with three dimensional
radiative energy, and a resolution of 600 km. The
unprecedented scale range is made possible by the new
DISPATCH code, which is explicitly constructed for the
exascale computing era, with the ability to scale to essentially
unlimited number of cores with sustained performance per
core. This is achieved by using task based scheduling, where
tasks do MHD, radiative energy transfer, and evolve the
positions of billions of pseudo-particles representing dust or
pebbles, using time steps restricted only by local condition.
Primary author
Prof.
Åke Nordlund
