Grain growth in the turbulent accretion disk solar nebula

The present characterization of grain-coagulation processes in the turbulent accretion-disk solar nebula gives attention to turbulent diffusion, radial shift, and the supply of grains by the accreting interstellar cloud. If it is assumed that only thermal convection maintains turbulence, the initial convection terminates in the inner region due to decreasing opacity and the nebula becomes both radiative and laminar. If accretion continues during the laminar phase, thermal convection could be intermittent, interstellar grains would increase opacity beyond the threshold value for thermal convection, and turbulent grain growth with laminar planetesimal formation would be repeated. 24 refs