Abstract Details
| status: | file name: | submitted: | by: |
|---|---|---|---|
| approved | zhu_sherwood2023.pdf | 2023-04-03 09:44:26 | Ben Zhu |
Abstracts
Author: Ben Zhu
Requested Type: Poster
Submitted: 2023-03-31 13:42:16
Co-authors: I.Joseph, A. Campos
Contact Info:
Lawrence Livermore National Laboratory
7000 East Ave, L-440
Livermore, CA 94550
USA
Abstract Text:
The Hasegawa-Wakatani (HW) model [1] and its extensions [2-4] are considered to be the minimal models that describe electrostatic drift-waves and the turbulence-zonal flow interaction. In this work, a new conducting HW (CHW) model is proposed that more accurately represents the drift-reduced Braginskii model for the geometry of a magnetically confined plasma. Simulations of the new CHM model are performed and compared to the original and modified HW models using both finite difference and conservative finite element [5] formulations. The CHW model is able to recover the turbulence bifurcation found in the modified HW model [3] since it also eliminates k∥ = 0 zonal damping. In the adiabatic limit, strong zonal flows are generated, turbulence is suppressed, and separate populations of drift-waves and zonal flows can be clearly identified. In the hydrodynamic limit, this model produces a mixed isotropic saturated turbulence (similar to the original 2D HW model [1]) along with low k⊥ convective cells (similar to the 3D HW model [2]), indicating a robust nonlinear energy transfer process from intermediate k∥ to low k∥. Moreover, unlike the extended HW model [4] which shows turbulence suppression with both good and bad curvature; when the CHW model is applied to curved magnetic fields by adding the interchange drive, a linear correlation between the turbulence dynamics and the curvature is found. Just as one would expect: in the bad curvature case, turbulence enhances and the dominant mode moves toward to a lower k; while in the good curvature case, turbulence is suppressed. Another advantage of simulating the CHW model is a significant relaxation of the Courant-Friedrichs-Lewy condition because the k → 0 singularity in the dispersion relation is eliminated. Therefore, a larger time-step compared to the original/modified HW models can be used to accelerate the simulation.
[1] Wakatani 1984 [2] Biskamp 1995 [3] Numata 2007 [4] Dewhurst 2009 [5] Holec 2022
Comments: