Turbulence in Particle-laden Midplane Layers of Planet-forming Disks

Abstract We examine the settled particle layers of planet-forming disks in which streaming instability (SI) is thought to be either weak or inactive. A suite low-to-moderate-resolution 3D simulations a 0.2 H -sized box, where pressure scale height, are performed using PENCIL for two Stokes numbers, St = 0.04 and 0.2, at 1% disk metallicity. find that complex Ekman-layer jet flows emerge subject three co-acting linearly growing processes: (1) Kelvin–Helmholtz (KHI), (2) analog baroclinic Symmetric Instability (SymI), (3) later-time weakly acting secondary transition process, possibly manifestation SI, producing radially propagating pattern state. For KHI dominant manifests as off-midplane axisymmetric rolls, while SymI mainly drives turbulence. analytically developed model flow, predicting it becomes strongly active when Richardson number (Ri) particle–gas midplane layer transitions below 1, exhibiting growth rates ? 2 / Ri ? · ? , ? local rotation rate. fairly general situations absent external sources turbulence conjectured if initiated, emerges out turbulent state primarily driven shaped by least and/or KHI. also produced 256 3 resolution not statistically converged corresponding 512 may 0.2. Furthermore, we report our numerical significantly dissipate kinetic energy on scales less than six eight grid points.