Streaming Instability
The streaming instability is a promising mechanism within protoplanetary disks to drive planetesimal formation from mm- to cm-sized pebbles which result from dust coagulation. Since its discovery by Youdin & Goodman (2005), several hydrodynamics codes have explored the parameters, non-linear properties, and implications 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 contribute to this project to review the Streaming Instability Code Comparison Problem Set (PDF). As this document continues to be developed, including the addition of new problems in future revisions, please contact Stanley A. Baronett with any questions or feedback that may be helpful toward future revisions.
GitHub Repository
Figure scripts and source codes related to this project can be found in our pfitsplus/sicc 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 contributing codes 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 first by model, next by problem, next by variation, and last by code.
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 contributing codes should be uploaded to our designated Google Shared Drive.
Anyone with the link can view and comment on the contents, but please contact Stanley A. Baronett to request access to add files.
To be consistent with the structure of the Problem Set (Section 1.2), the subdirectories therein are hierarchically organized first by model, next by problem, next by variation, and last by code.
Regardless of the inherent data format normally generated by a contributing code, all requested output (e.g., arrays) must be stored in or converted to individual compressed 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
Lagrangian dust particles
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 \(H_\mathrm{g}\).
Maximum dust density as a function of time for codes implementing Lagrangian particles.
Line colours represent different codes.
Densities are normalised to the initially uniform gas density \(\rho_\mathrm{g,0}\).
Time-averaged cumulative distribution functions for the dust density for codes implementing Lagrangian particles.
Solid lines represent the time-averaged densities, shaded areas represent the \(1\sigma\) time variability, and different colours represent different codes.
Pressureless dust fluid
A series of snapshots of the dust density field from various fluid-dust codes for Problem BA 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 \(H_\mathrm{g}\).
Maximum dust density as a function of time for codes implementing a pressureless fluid.
Line colours represent different codes.
Densities are normalised to the initially uniform gas density \(\rho_\mathrm{g,0}\).
Time-averaged cumulative distribution functions for the dust density for codes implementing Lagrangian particles.
Solid lines represent the time-averaged densities, shaded areas represent the \(1\sigma\) time variability, and different colours represent different codes.