# Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime

## Abstract

In this paper, the interface width effects (i.e., the density gradient effects or the density transition layer effects) on the Rayleigh-Taylor instability (RTI) in the weakly nonlinear (WN) regime are investigated by numerical simulation (NS). It is found that the interface width effects dramatically influence the linear growth rate in the linear growth regime and the mode coupling process in the WN growth regime. First, the interface width effects decrease the linear growth rate of the RTI, particularly for the short perturbation wavelengths. Second, the interface width effects suppress (reduce) the third-order feedback to the fundamental mode, which induces the nonlinear saturation amplitude (NSA) to exceed the classical prediction, 0.1lambda. The wider the density transition layer is, the larger the NSA is. The NSA in our NS can reach a half of its perturbation wavelength. Finally, the interface width effects suppress the generation and the growth of the second and the third harmonics. The ability to suppress the harmonics' growth increases with the interface width but decreases with the perturbation wavelength. On the whole, in the WN regime, the interface width effects stabilize the RTI, except for an enhancement of the NSA, which is expected to improve the understanding ofmore »

- Authors:

- LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
- (China)
- State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China)

- Publication Date:

- OSTI Identifier:
- 21371107

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physics of Plasmas; Journal Volume: 17; Journal Issue: 5; Other Information: DOI: 10.1063/1.3396369; (c) 2010 American Institute of Physics

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; INSTABILITY GROWTH RATES; INTERFACES; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PLASMA DENSITY; RAYLEIGH-TAYLOR INSTABILITY; FLUID MECHANICS; HYDRODYNAMICS; INSTABILITY; MECHANICS; SIMULATION

### Citation Formats

```
Wang, L. F., State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083, Ye, W. H., Department of Physics, Zhejiang University, Hangzhou 310027, China and CAPT, Peking University, Beijing 100871, and Li, Y. J.
```*Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime*. United States: N. p., 2010.
Web. doi:10.1063/1.3396369.

```
Wang, L. F., State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083, Ye, W. H., Department of Physics, Zhejiang University, Hangzhou 310027, China and CAPT, Peking University, Beijing 100871, & Li, Y. J.
```*Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime*. United States. doi:10.1063/1.3396369.

```
Wang, L. F., State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083, Ye, W. H., Department of Physics, Zhejiang University, Hangzhou 310027, China and CAPT, Peking University, Beijing 100871, and Li, Y. J. Sat .
"Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime". United States.
doi:10.1063/1.3396369.
```

```
@article{osti_21371107,
```

title = {Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime},

author = {Wang, L. F. and State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 and Ye, W. H. and Department of Physics, Zhejiang University, Hangzhou 310027, China and CAPT, Peking University, Beijing 100871 and Li, Y. J.},

abstractNote = {In this paper, the interface width effects (i.e., the density gradient effects or the density transition layer effects) on the Rayleigh-Taylor instability (RTI) in the weakly nonlinear (WN) regime are investigated by numerical simulation (NS). It is found that the interface width effects dramatically influence the linear growth rate in the linear growth regime and the mode coupling process in the WN growth regime. First, the interface width effects decrease the linear growth rate of the RTI, particularly for the short perturbation wavelengths. Second, the interface width effects suppress (reduce) the third-order feedback to the fundamental mode, which induces the nonlinear saturation amplitude (NSA) to exceed the classical prediction, 0.1lambda. The wider the density transition layer is, the larger the NSA is. The NSA in our NS can reach a half of its perturbation wavelength. Finally, the interface width effects suppress the generation and the growth of the second and the third harmonics. The ability to suppress the harmonics' growth increases with the interface width but decreases with the perturbation wavelength. On the whole, in the WN regime, the interface width effects stabilize the RTI, except for an enhancement of the NSA, which is expected to improve the understanding of the formation mechanism for the astrophysical jets, and for the jetlike long spikes in the high energy density physics.},

doi = {10.1063/1.3396369},

journal = {Physics of Plasmas},

number = 5,

volume = 17,

place = {United States},

year = {Sat May 15 00:00:00 EDT 2010},

month = {Sat May 15 00:00:00 EDT 2010}

}