### The effect of artificial bulk viscosity in simulations of forced compressible turbulence

The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performance of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improvedmore »

- Publication Date:

- Report Number(s):
- LLNL-JRNL-739678

Journal ID: ISSN 0021-9991; 893182

- Grant/Contract Number:
- AC52-07NA27344

- Type:
- Accepted Manuscript

- Journal Name:
- Journal of Computational Physics

- Additional Journal Information:
- Journal Volume: 371; Journal Issue: C; Journal ID: ISSN 0021-9991

- Publisher:
- Elsevier

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

- Sponsoring Org:
- USDOE National Nuclear Security Administration (NNSA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICS AND COMPUTING; arti cial viscosity; compressible turbulence; large-eddy simulation

- OSTI Identifier:
- 1455410

```
Campos, A., and Morgan, B..
```*The effect of artificial bulk viscosity in simulations of forced compressible turbulence*. United States: N. p.,
Web. doi:10.1016/j.jcp.2018.05.030.

```
Campos, A., & Morgan, B..
```*The effect of artificial bulk viscosity in simulations of forced compressible turbulence*. United States. doi:10.1016/j.jcp.2018.05.030.

```
Campos, A., and Morgan, B.. 2018.
"The effect of artificial bulk viscosity in simulations of forced compressible turbulence". United States.
doi:10.1016/j.jcp.2018.05.030.
```

```
@article{osti_1455410,
```

title = {The effect of artificial bulk viscosity in simulations of forced compressible turbulence},

author = {Campos, A. and Morgan, B.},

abstractNote = {The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performance of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improved forcing function that explicitly accounts for the role of the artificial bulk viscosity in the budget of turbulent kinetic energy was explored.},

doi = {10.1016/j.jcp.2018.05.030},

journal = {Journal of Computational Physics},

number = C,

volume = 371,

place = {United States},

year = {2018},

month = {5}

}