Overview of capabilities
This page provides an overview of the main capabilities of the code.
Grids, fixed and variable weight DSMC
| 0D | 1D | |
|---|---|---|
| Fixed-weight DSMC | ✅ | ✅ |
| Variable-weight DSMC | ✅ | ✅ |
Currently, simulations are either 0D (spatially homogeneous) or on a uniform 1D grid. For 1D simulations, specular and diffuse reflection models are available (along with a mixture of the two via an accommodation coefficient).
Collisions
The No-Time-Counter (NTC) approach of Bird (1994) is implemented for fixed-weight DSMC. The variable-weight NTC approach of Schmidt and Rutland (2000) is implemented for variable-weight DSMC. Event splitting (Oblapenko et al. (2022)) is implemented for neutral-electron interactions.
Fokker-Planck collisions
As an alternative to DSMC, one can use the stochastic Fokker-Planck algorithm to simulate the particle collisions. Currently, the linear Fokker-Planck model of Gorhi, Torrilhon, and Jenny (2011) is implemented for fixed-weight particles.
| Linear | Cubic | |
|---|---|---|
| Fixed-weight Fokker-Planck | ✅ | ❌ |
| Variable-weight Fokker-Planck | ❌ | ❌ |
Particle merging algorithms
The following particle merging algorithms are available for variable-weight DSMC simulations:
- A grid-based merging algorithm as described in Oblapenko et al. (2020) (see also Vranic et al. (2015))
- The octree merging algorithm of Martin and Cambier (2016)
- A Non-Negative Least Squares (NNLS)-based merging approach described in Oblapenko (2024)
- The roulette merge of Watrous, Seidel et al (2023)
Cross-sections
The Variable-Hard Sphere (VHS) model is implemented for collisions of neutral particles. For neutral-electron collisions, LXCat data in XML format needs to be provided for the elastic scattering and electron-impact ionization cross-sections. Currently, only isotropic scattering is implemented for neutral-electron collisions.
Inelastic collisions
In flows with neutrals, ions, and electrons, electron-impact ionization is supported. Variable weight DSMC simulations also support the Event Splitting (ES) collision algorithm of Oblapenko et al. (2022).
External fields
Acceleration of charged particles by a constant electric field is supported.
I/O
The code assumes the TOML format for the particle and VHS interaction data. XML is used for the LXCat data. Output of the computed macroscopic properties is in NetCDF4 format.
Parallel computations
Multithreading is supported via domain decomposition, see the section on setting up multithreaded simulations for more details. Multithreaded variable-weight DSMC computations have not been tested yet.