HiPS (Hierarchical Parcel Swapping)

This code implements the Hierarchal Parcel Swapping (HiPS) model for turbulent reacting or nonreacting flows.

Documentation is available at ignite.byu.edu/hips_documentation

• Publications

  • Behrang et al. (2025): A C++ library for turbulent mixing simulation using hierarchical parcel swapping (HiPS), SoftwareX, accepted for publication.
  • Behrang et al. (2025): Turbulent Mixing of Scalars with Nonunity Schmidt Numbers Using Hierarchical Parcel-Swapping, Journal of Fluid Mechanics, accepted for publication. Paper.
  • Kerstein (2021): Hierarchical Parcel-Swapping Representation of Turbulent Mixing. Part 3. Origins of Correlation Patterns Observed in Turbulent Boundary Layers, Physical Review Fluids, 6:044611.
  • Kerstein (2014): Hierarchical Parcel-Swapping Representation of Turbulent Mixing. Part 2. Application to Channel Flow, Journal of Fluid Mechanics, 750:421–463.
  • Kerstein (2013): Hierarchical Parcel-Swapping Representation of Turbulent Mixing. Part 1. Formulation and Scaling Properties, Journal of Statistical Physics, 153:142–161.

Directory Structure

• build/: This directory is not included by default and must be created by the user.

  • To compile the code, navigate to this directory and run: bash cmake .. make make install make documentation # Optional: only if documentation is desired

• src/: Contains all source code for the HiPS implementation.

• example/: Contains three default example cases that users can run to get started.

• run/: Contains the compiled executables generated during the build process.

• post/: Contains Python scripts for post-processing.

  • When users run an example case, a file named parameters.dat is automatically saved in the post/ folder. This file records the parameters used for the run, which may be required by the post-processing scripts.
  • Post-processing results are saved into a subfolder named processed_data/, created automatically inside the corresponding post/ directory.

• data/: Created only if data writing is enabled during execution.

  • This happens when the function: cpp void calculateSolution(const double tRun, bool shouldWriteData = true); is called with shouldWriteData set to true.
  • A subfolder is generated with a name corresponding to the case name specified in the run script (e.g., rlz_00001 by default).
  • The number of realization folders corresponds to the number of realizations specified by the user.

• docs/: Contains documentation built with Doxygen.

• test/: contains unit/integration tests using the Catch2 library. There is a git hook in .githooks/pre-push that runs the tests before the code can be pushed.

  • configure the hook location by running git config core.hooksPath .githooks

Dependencies

HiPS code

• CMake ≥ 3.15: build configuration and code compilation.
• C++11-compatible compiler: required to compile the code.
• (OPTIONAL) Cantera: open-source suite for chemical kinetics, thermodynamics, and transport.
  • Only needed if reactions are enabled via -DREACTIONS_ENABLED=ON in the CMake configuration.
• (OPTIONAL) SUNDIALS: required only for the CVODE integrator used in reaction-enabled builds.
• (OPTIONAL) Doxygen: used to build code documentation from annotated source files.
• (OPTIONAL) Catch2: library for unit tests.
  • Only available if the HIPS_BUILD_TESTS flag is on, in which case the Catch2 library should be available of the system.

Post-processing

Post-processing of simulation data is performed using Python 3 scripts. We recommend Python 3.6 or higher. The following packages are required and can be installed via pip:

• numpy
• scipy
• matplotlib
• glob (built-in)
• os (built-in)
• sys (built-in)