## Extension of Landau-fluid closure to weakly collisional plasma regime

## Abstract

Both collisionless and collisional Landau fluid (LF) closure have been developed and implemented in two-fluid plasma simulation framework BOUT++, taking full advantage of the fast non-Fourier method (Dimits, 2014). The spectral range of good fit can be conveniently extended to larger domain by adding more Lorentzians. The scaling for upper limit of wavenumber resolved in collisionless LF operator and the fitting coefficients for the collisional LF operator, the later is extended to weakly collisional regime (ν$$^{*}_{e}$$ ~ 0.01), are presented in this paper. The flux limited expression q$$^{FL}_{∥e}$$ is reduced to free streaming expression q$$^{FS}_{∥e}$$ in collisionless limit and gives classical Spitzer–Härm result q$$^{SH}_{∥e}$$ in collisional limit as we expected. The collisional LF closure recovers the classical Spitzer–Härm result q$$^{SH}_{∥e}$$ in collisional limit and is same as the collisionless LF closure in collisionless limit. The test cases also obviously reflect the nonlocal effects from LF closures and responding to different boundary conditions in open surface region. Our report will make it more applicable and possible to include the Landau damping kinetic effect in the fluid simulation of tokamak plasma.

- Authors:

- Peking Univ., Beijing (China); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Peking Univ., Beijing (China)

- Publication Date:

- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA); National Natural Science Foundations of China (NNSFC); China Scholarship Council

- OSTI Identifier:
- 1566023

- Report Number(s):
- LLNL-JRNL-748335

Journal ID: ISSN 0010-4655; 933485

- Grant/Contract Number:
- AC52-7NA27344; 2013GB111000; 2013GB112006; 201606010047; 11261140326; 11375053

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Computer Physics Communications

- Additional Journal Information:
- Journal Volume: 236; Journal Issue: C; Journal ID: ISSN 0010-4655

- Publisher:
- Elsevier

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Parallel heat flux; Landau resonance closure; Non-Fourier method; Weakly collisional regime; BOUT++

### Citation Formats

```
Chen, J. G., Xu, X. Q., and Lei, Y. A. Extension of Landau-fluid closure to weakly collisional plasma regime. United States: N. p., 2018.
Web. doi:10.1016/j.cpc.2018.10.024.
```

```
Chen, J. G., Xu, X. Q., & Lei, Y. A. Extension of Landau-fluid closure to weakly collisional plasma regime. United States. doi:10.1016/j.cpc.2018.10.024.
```

```
Chen, J. G., Xu, X. Q., and Lei, Y. A. Mon .
"Extension of Landau-fluid closure to weakly collisional plasma regime". United States. doi:10.1016/j.cpc.2018.10.024. https://www.osti.gov/servlets/purl/1566023.
```

```
@article{osti_1566023,
```

title = {Extension of Landau-fluid closure to weakly collisional plasma regime},

author = {Chen, J. G. and Xu, X. Q. and Lei, Y. A.},

abstractNote = {Both collisionless and collisional Landau fluid (LF) closure have been developed and implemented in two-fluid plasma simulation framework BOUT++, taking full advantage of the fast non-Fourier method (Dimits, 2014). The spectral range of good fit can be conveniently extended to larger domain by adding more Lorentzians. The scaling for upper limit of wavenumber resolved in collisionless LF operator and the fitting coefficients for the collisional LF operator, the later is extended to weakly collisional regime (ν$^{*}_{e}$ ~ 0.01), are presented in this paper. The flux limited expression q$^{FL}_{∥e}$ is reduced to free streaming expression q$^{FS}_{∥e}$ in collisionless limit and gives classical Spitzer–Härm result q$^{SH}_{∥e}$ in collisional limit as we expected. The collisional LF closure recovers the classical Spitzer–Härm result q$^{SH}_{∥e}$ in collisional limit and is same as the collisionless LF closure in collisionless limit. The test cases also obviously reflect the nonlocal effects from LF closures and responding to different boundary conditions in open surface region. Our report will make it more applicable and possible to include the Landau damping kinetic effect in the fluid simulation of tokamak plasma.},

doi = {10.1016/j.cpc.2018.10.024},

journal = {Computer Physics Communications},

number = C,

volume = 236,

place = {United States},

year = {2018},

month = {11}

}