Introduction

RAPID (Representative Approach for Particle-Integrated Disks) is a one-dimensional numerical code designed to simulate the coupled evolution of gas and dust in protoplanetary disks. It combines an Eulerian description of the gas with a Lagrangian representation of the dust, enabling the simultaneous modeling of viscous gas evolution, dust radial drift, and particle growth.

The code is designed to investigate the dynamical and physical processes that shape the structure and evolution of protoplanetary disks, including the formation of pressure traps, the effects of dead zones, and the role of photoevaporation in disk dispersal.

This documentation describes the physical model, numerical methods, and practical use of RAPID. The following sections introduce the underlying physical background and governing equations before detailing the code’s implementation and usage.