Spectral treatment of gyrokinetic shear flow

JOURNAL OF COMPUTATIONAL PHYSICS

卷:356

Article

Candy, J.¹  Belli, E. A.¹ 

[1] Gen Atom, POB 85608, San Diego, CA 92186 USA

关键词: Gyrokinetic;    Shear;    Flow;   

DOI  :  10.1016/j.jcp.2017.12.020

来源: Elsevier

【 摘 要 】

Sheared E x B flow in a tokamak, driven by external torque from neutral beam injection, is known to have an important stabilizing effect on drift-wave turbulence. In gyrokinetic codes, flow shear can be implemented directly on a radial mesh with nonperiodic boundary conditions. The mesh-based implementation is straightforward, but carries the possibility of spurious effects related to simulation boundaries. Alternatively, flow shear has been implemented in spectral solvers using a wavenumber shift method. Although the spectral representation has numerous computational benefits, the wavenumber shift method for treating flow shear is of questionable accuracy. Efforts to compare mesh-based solutions with spectral ones have met with limited success. In particular, significant differences in the critical shear required to stabilize turbulence are sometimes observed. We outline a new approach to treat flow shear spectrally. The method is simple to implement, matches the nonperiodic results more closely, and predicts a critical shear that is less sensitive to radial wavenumber resolution. (C) 2017 Elsevier Inc. All rights reserved.

【 授权许可】

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