Numerical simulation of the geometrical-optics reduction of CE2 and comparisons to quasilinear dynamics
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Zonal flows have been observed to appear spontaneously from turbulence in a number of physical settings. A complete theory for their behavior is still lacking. Recently, a number of studies have investigated the dynamics of zonal flows using quasilinear (QL) theories and the statistical framework of a second-order cumulant expansion (CE2). A geometrical-optics (GO) reduction of CE2, derived under an assumption of separation of scales between the fluctuations and the zonal flow, is studied here numerically. The reduced model, CE2-GO, has a similar phase-space mathematical structure to the traditional wave-kinetic equation, but that wave-kinetic equation has been shown to fail to preserve enstrophy conservation and to exhibit an ultraviolet catastrophe. CE2-GO, in contrast, preserves nonlinear conservation of both energy and enstrophy. We show here how to retain these conservation properties in a pseudospectral simulation of CE2-GO. We then present nonlinear simulations of CE2-GO and compare with direct simulations of quasilinear (QL) dynamics. Furthermore, we find that CE2-GO retains some similarities to QL.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1466924
- Alternate ID(s):
- OSTI ID: 1427890
- Report Number(s):
- LLNL-JRNL-742576; 897424
- Journal Information:
- Physics of Plasmas, Vol. 25, Issue 5; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
On the structure of the drifton phase space and its relation to the Rayleigh–Kuo criterion of the zonal-flow stability
|
journal | July 2018 |
Formation of solitary zonal structures via the modulational instability of drift waves
|
journal | May 2019 |
Wave kinetic equation for inhomogeneous drift-wave turbulence beyond the quasilinear approximation | text | January 2019 |
Similar Records
Zonal Flows and Turbulence in Fluids and Plasmas
On the structure of the drifton phase space and its relation to the Rayleigh–Kuo criterion of the zonal-flow stability