Yue Sun and Chris H. Rycroft, A fully-integrated lattice Boltzmann method for fluid–structure interaction, preprint (2024) [arXiv preprint]
The LBRMT is designed to simulate fluid–structure interaction (FSI).
As an Eulerian method, it only requires one fixed computational grid for both solids and fluids. The LBRMT consists of two integral parts: the first involves an Eulerian representation of finite-strain solids, and the second involves a boundary condition for moving deformable interfaces across different densities. We use the reference map technique (RMT) to model solid large deformation. Additionally, we have developed a new lattice Boltzmann (LB) boundary condition called "smooth flux correction" to model the interfaces between squishy solids and fluids.
The LBRMT is suitable for parallelization and capturing the multi-body contact of hundreds of solids. It can simulate soft solids rotating, settling, floating, and mixing. We believe it could be a promising tool for simulating the spatiotemporal patterns of active matter and studying both the collective and individual dynamics of biological systems.
- One grid to run them all: no extra meshes or remeshing needed to track solids
- From Boltzmann to lattice Boltzmann: easy to parallelize for fluid simulation
- The more, the merrier: efficient to model hundreds of soft solids
If a picture is worth a thousand words, check out our simulation videos!
The code is written in C++ and uses the OpenMP library for multithreading. It has been tested on Linux and MacOS (GCC installed via Homebrew). The following compiling instructions assume that you have a working C++ environment with OpenMP on your computer. All commands are in the terminal.
First, navigate to the directory that you want to install LBRMT then clone the repo:
git clone https://github.com/yue-sun/lbrmt.gitSecond, navigate into lbrmt and compile:
cd lbrmt
makeNow your executables should be in the build/ and ready to run!
⚠️ GCC: If you're a Mac user, make sure yourGCCis in/opt/homebrew/bin/gccwhen you typewhich gcc. Also, adjust theGCCversion in theMakefileaccording to yourGCCversion.
After successfully compiling the code, you should have the following directories within lbrmt/:
lbrmt
│ README.md
│ Makefile
└───build # simulation executables (autogenerated)
│ │ sim_fsi # exec for lid-driven cavity and settling/floating
│ │ sim_rotate # exec for rotating
│ └───sim_mix # exec for mixing
└───objs # objects and linker files (autogenerated)
└───src # code source files
└───sims # examples (config files, simulation results also saved here)
│ │ fsi_ldc.cfg # lid-driven cavity with a soft solid
│ │ fsi_rotate.cfg # 4 anchored rotors rotating
│ │ fsi_settle.cfg # 1 solid settling or floating
│ └───fsi_mix.cfg # 100 solids mixing
└───utils # scripts for visualization and data processingThe benchmark example (Section 4.1) of a soft solid in lid-driven cavity can be run using two threads with the following command:
OMP_NUM_THREADS=2 build/sim_fsi sims/fsi_ldc.cfgThe config file specifies the simulation parameters, such as domain size, geometric and material properties for the solid, and physical properties for the fluid. The code will create a directory called fsi_ldc.out for the simulation output under the sims/ directory. To process the output data, navigate to the utils directory and there are Python scripts and notebooks to postprocess for data analysis and visualization.
To modify the simulation domain size or solid/fluid properties, modify the *.cfg files.
To run other examples, follow the similar command structure:
OMP_NUM_THREADS=(num_threads) build/(your_exec) sims/(your_sim).cfg
⚠️ If you run into complication or running errors, please either create a New issue on GitHub or contact Yue Sun via email.
- Solids at wall boundaries: Currently can only handle
bctype==3(fully no-slip box); other wall boundary conditions will be added - Consolidate executables
- Make the entire extrapolation routine parallel
- Simulate microswimmers
If you use this code in your research or anywhere, please cite the preprint:
@misc{sun2024fullyintegrated,
title = {A fully-integrated lattice {{Boltzmann}} method for fluid--structure interaction},
author = {Sun, Yue and Rycroft, Chris H.},
year = {2024},
number = {arXiv:2402.12696},
eprint = {2402.12696},
primaryclass = {physics},
publisher = {arXiv},
doi = {10.48550/arXiv.2402.12696},
archiveprefix = {arxiv}
}| Code | Paper |
|---|---|
 |
Reference map technique for incompressible fluid-structure interaction |
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Eulerian simulation of complex suspensions and biolocomotion in three dimensions |
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Ken Kamrin, Stochastic and deterministic models for dense granular flow, Ph.D. thesis, Massachusetts Institute of Technology (2008). DSpace
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Ken Kamrin and Jean-Christophe Nave, An Eulerian approach to the simulation of deformable solids: application to finite-strain elasticity, arXiv:0901.3799 (2009).
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Ken Kamrin, Chris H. Rycroft, and Jean-Christophe Nave, Reference map technique for finite-strain elasticity and fluid–solid interaction, Journal of the Mechanics and Physics of Solids 60, 1952–1969 (2012). doi:10.1016/j.jmps.2012.06.003
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Boris Valkov, Chris H. Rycroft, and Ken Kamrin, Eulerian method for multiphase interactions of soft solid bodies in fluids, Journal of Applied Mechanics 82, 041011 (2015). doi:10.1115/1.4029765
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Chris H. Rycroft, Chen-Hung Wu, Yue Yu, and Ken Kamrin, Reference map technique for incompressible fluid-structure interaction, Journal of Fluid Mechanics 898, A9 (2020). doi:10.1017/jfm.2020.353
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Yuexia Luna Lin, Nicolas J. Derr, and Chris H. Rycroft, Eulerian simulation of complex suspensions and biolocomotion in three dimensions, Proc. Natl. Acad. Sci. 119, e2105338118 (2022). doi:10.1073/pnas.2105338118
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Xiaolin Wang, Ken Kamrin, and Chris H. Rycroft, An Eulerian method for mixed soft and rigid body interactions in incompressible fluids, Physics of Fluids 34, 033604 (2022). doi:10.1063/5.0082233