Speaker
Description
Convective Overstability (COS) is a hydrodynamic instability in protoplanetary discs (PPDs) that is thought to form large-scale structures like zonal flows (or pressure bumps) and vortices. These structures are supposed to trap dust grains, potentially accelerating planetesimal formation. However, current numerical models rely heavily on periodic vertical boundary conditions (VBCs). Because periodic VBCs can sustain zonal flows accompanied by vertical elevator flows, they artificially imply infinite upward and downward fluid motion, which is physically unrealistic. This raises the critical question of whether the resulting dust-trapping structures are physical phenomena or merely numerical artifacts. To test the robustness of the COS, we evaluated its evolution under more realistic, non-periodic VBCs: zero heat flux and zero perturbation. Utilizing an unstratified Boussinesq shearing box model, we conducted linear theory analysis and 2D axisymmetric nonlinear simulations with the DEDALUS code. We found that non-periodic VBCs suppressed both zonal and elevator flows, calling into question the efficacy of the COS in facilitating planetesimal formation.
| Participate the oral/poster presentation award competition | Yes |
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