Dynamics of small, constant size particles in a protoplanetary disk with an embedded protoplanet

TL;DR

This paper improves protoplanetary disk simulations by replacing the constant Stokes number assumption with a constant particle size approach, revealing significant differences in disk morphology and particle fluxes near planets.

Contribution

It introduces a semi-analytic method to implement constant particle size in hydrodynamical simulations, enhancing accuracy over the traditional constant Stokes number approximation.

Findings

Constant particle size assumption affects disk morphology significantly.

Particle fluxes across planetary gaps differ with the new approach.

The method improves the realism of dust-gas interaction modeling.

Abstract

Hydrodynamical simulations of protoplanetary disk dynamics are useful tools for understanding the formation of planetary systems, including our own. Approximations are necessary to make these simulations computationally tractable. A common assumption when simulating dust fluids is that of a constant Stokes number, a dimensionless number that characterizes the interaction between a particle and the surrounding gas. Constant Stokes number is not a good approximation in regions of the disk where the gas density changes significantly, such as near a planet-induced gap. In this paper, we relax the assumption of constant Stokes number in the popular FARGO3D code using semi-analytic equations for the drag force on dust particles, which enables an assumption of constant particle size instead. We explore the effect this change has on disk morphology and particle fluxes across the gap for both outward- and inward-drifting particles. The assumption of constant particle size, rather than constant Stokes number, is shown to make a significant difference in some cases, emphasizing the importance of the more accurate treatment.