thunderboltz 0.1.0

A 0D Direct Simulation Monte-Carlo code for the calculation of transport coefficients and 0D gas modeling.

ThunderBoltz

ThunderBoltz is a 0D Direct Simulation Monte-Carlo code for the calculation of transport coefficients and 0D gas modeling. This repository contains the ThunderBoltz C++ source code (C22063) and ThunderBoltz Python API code (O4674), which are released with a GPL v3 license. The overarching goal of this project is to provide transport coefficients for electrons, ions and neutrals, and to model energy transfer between charged particles and neutral gases. These processes are not modeled by commonly used Boltzmann solvers such as Bolsig+ or MagBoltz since these solvers only track electron transport (either via trajectories in the MC case, or through modeling of the EEDF) due to collisions with a stationary neutral background.

To reference this code and work, please cite the arXiv article: https://arxiv.org/abs/2310.07913

Manuals

The ThunderBoltz C++ source code manual is found in the home directory "cpp_manual.pdf", and the Python API code manual is found in the home directory "api_manual.pdf".

Installation

Clone the repository

Clone a local repository with the code. You may need to set up SSH keys in order to access gitlab. See here.

git clone https://github.com/lanl/ThunderBoltz.git

The basic ThunderBoltz functionality will be available either as an executable in bin/thunderboltz.bin or can be compiled from the source in src/thunderboltz.

Usage

For ease of use, we recommend using the Python interface to setup, run, and process simulations (see here). Alternatively, one can use the stand-alone C++ code to run calculations (below).

Manual compilation and execution (ThunderBoltz code only)

The C++ source files are located in src/thunderboltz/cpp/. ThunderBoltz requires a g++ of clang compiler and should be compiled from source directories as

g++ -std=c++17 -o thunderboltz.bin DSMC0D.cpp

Then run with

./thunderboltz.bin inputfile.in

to use a manually constructed indeck file. The code is maintained with the standard -Wall and -Werror compiler options.

Here is an example of how to run a simple ThunderBoltz calculation.

# Make a directory for testing
mkdir example_sim
cd example_sim
# Copy the source over
cp ../src/thunderboltz/cpp/* .
# Copy example input files over
cp -r ../indecks/N2/* .
# Compile
g++ -std=c++17 -o thunderboltz.bin DSMC0D.cpp
# Run
./thunderboltz.bin N2vib.in

Simulation parameters can be adjusted in the N2vib.in file for this example.

Using the Python wrapper

We also include a python wrapper that allows for automated compilation and extended input/output processing. To install the python API from the repository, run the install.sh script from the root directory:

./install.sh

This will upgrade pip and install specific versions of python packages, so create an environment if you are concerned with python package overwrite.

See run.py for implementations of the tests found in the paper using the API wrapper.

Testing and code sync

Make sure a version of pytest is installed:

pip install pytest

To run unit tests on the python thunderboltz package, run

python -m pytest testing/*.py --verbose

To recompile the standalone binary version, run

g++ -std=c++17 src/thunderboltz/cpp/DSMC0D.cpp -o bin/thunderboltz.bin -Wall -Werror -Wsign-compare

License

ThunderBoltz is distributed under a GNU GPLv3 license. See http://www.gnu.org/licenses/gpl-3.0.en.html for more details.

Roadmap

• Regression testing of internal ThunderBoltz code
• Diffusion post processing
• Random deletion after ionization option
• Addition of photon transport