We present high-resolution computer simulations of dust dynamics and planetesimal formation in turbulence generated by the magnetorotational instability .
We show that the turbulent viscosity associated with magnetorotational turbulence in a non-stratified shearing box increases when going from 256 ^ { 3 } to 512 ^ { 3 } grid points in the presence of a weak imposed magnetic field , yielding a turbulent viscosity of \alpha \approx 0.003 at high resolution .
Particles representing approximately meter-sized boulders concentrate in large-scale high-pressure regions in the simulation box .
The appearance of zonal flows and particle concentration in pressure bumps is relatively similar at moderate ( 256 ^ { 3 } ) and high ( 512 ^ { 3 } ) resolution .
In the moderate-resolution simulation we activate particle self-gravity at a time when there is little particle concentration , in contrast with previous simulations where particle self-gravity was activated during a concentration event .
We observe that bound clumps form over the next ten orbits , with initial birth masses of a few times the dwarf planet Ceres .
At high resolution we activate self-gravity during a particle concentration event , leading to a burst of planetesimal formation , with clump masses ranging from a significant fraction of to several times the mass of Ceres .
We present a new domain decomposition algorithm for particle-mesh schemes .
Particles are spread evenly among the processors and the local gas velocity field and assigned drag forces are exchanged between a domain-decomposed mesh and discrete blocks of particles .
We obtain good load balancing on up to 4096 cores even in simulations where particles sediment to the mid-plane and concentrate in pressure bumps .