Streaming Instability
The streaming instability is a promising mechanism to drive planetesimal formation from mm- to cm-sized pebbles, resulting from dust coagulation, all of which occur within the gaseous protoplanetary disk. Since its discovery by Youdin & Goodman (2005), several hydrodynamics codes have explored the parameters, properties, and consequences of this aerodynamic instability that requires feedback between dust and gas momenta. However, the non-trivial differences between numerical techniques (e.g., finite difference or finite volume) and dust modeling (e.g., as a pressureless fluid or as Lagrangian particles) can make it difficult to disentangle unique scientific results from the potential idiosyncrasies of a particular code or implementation. In an effort to address these issues, we are leading a comprehensive comparison of various multipurpose codes across some of the key models and problems previously studied in investigations into the streaming instability.
Problem Set
We invite users and developers of hydrodynamical codes who wish to participate or contribute to this project to review the Streaming Instability Code Comparison Problem Set (PDF). As this document continues to be developed, please contact Stanley A. Baronett with any questions or feedback that may be helpful toward future revisions.
GitHub Repository
Project and source files related to this project can be found in our associated GitHub repository.
Jupyter Notebooks containing Python scripts to generate the figures below and in our forthcoming manuscript can be found in the /ipynb directory.
Source and input files for some participating codes, as well as pseudo code for particular models, can be found in the /source_files directory.
To be consistent with the structure of the Problem Set (Section 1.2), the subdirectories therein are hierarchically organized by model, by problem, then by variation.
For more information, please see the repository README, and feel free to create an issue for any questions, feedback, or issues encountered.
Google Shared Drive
The problem data outputted by participating codes for submission to the project should be uploaded to our designated Google Shared Drive.
To be consistent with the structure of the Problem Set (Section 1.2), the subdirectories therein are hierarchically organized by model, by problem, by variation, then by code.
Regardless of the inherent data format normally generated by a participating code, all requested output (e.g., arrays) must be converted to (i.e. stored in) individual compressed or uncompressed NumPy .npz files (see the official “Input and output” documentation for details).
Further details on the structure and contents of submission data can be found in Section 1.1.2 of the Problem Set.
Preliminary Figures
A series of snapshots of the dust density field from various Lagrangian-dust codes for Problem BA with an average of one particle per gas cell, i.e. \(n_\mathrm{p} = 1\), at a grid resolution of \(512 \times 512\) (see Section 2.2.1 of the Problem Set).
Increasing from top to bottom, each row corresponds to the simulation time \(t_\mathrm{sim}\) in units of the local orbital period \(T\), as labeled along the left margin.
In alphabetical order from left to right, each column corresponds to a different code, as labeled along the top row of snapshots.
The color-bar scale in the bottom right indicates the dust density \(\rho_\mathrm{p}\) in units of the initially uniform gas density \(\rho_\mathrm{g,0}\).
Radial \(x\) and vertical \(z\) coordinates are in units of the vertical gas scale height \(H_\mathrm{g}\).