Abstract Details
Abstracts
Author: Federico D Halpern
Requested Type: Poster
Submitted: 2023-03-30 18:49:57
Co-authors: R.E. Waltz, T.N. Bernard, M. Peret
Contact Info:
General Atomics
PO Box 85608
San Diego, 92186
United States
Abstract Text:
Transport and turbulence codes based on drift-fluid models constitute an integral part of predictive workflows for current and future tokamaks. This work discusses our progress removing many of the existing pitfalls in drift-fluid codes. In particular, although drift-ordered fluid codes are widely applied in tokamak edge turbulence simulations, the models used are acknowledged not to conserve energy or even electrical charge. Our main result is an improved version of the drift-Braginskii equations involving a generalized vorticity function. In the new drift-Braginskii model, the Reynolds stresses are manifestly expressed as a vorticity flow, which is crucial for a proper numerical treatment. It is found that kinetic energy conservation can be achieved if the polarization flow is defined recursively. The resulting model conserves the kinetic energy associated with ExB and diamagnetic flows and retains the associated perpendicular kinetic energy flux [1]. We show the first simulations of blobby transport using the new formalism, as implemented in the ALMA numerical engine [2]. Our implementation does not yet capture the recursive definition of the polarization velocity, but retains some higher-order kinetic energy corrections, and implements the correct non-Boussinesq Poisson equation. These first demonstrations illustrate the potential of our new formalism to impact the quality of results from drift-fluid codes. -- This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, Theory Program, under Award No. DE-FG02-95ER54309.
[1] F.D. Halpern, R.E. Waltz, T.N. Bernard, Phys Plasmas 30, 032302 (2023)
[2] F.D. Halpern et al., Journal of Computational Physics 445, 110631 (2021)
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