Abstract Details
Abstracts
Author: Sanket A. Patil
Requested Type: Poster
Submitted: 2023-03-31 19:17:46
Co-authors: Carl R. Sovinec, Chris C. Hegna
Contact Info:
UNIVERSITY OF WISCONSIN-MADISON
120 N Franklin St, 2
MADISON, WISCONSIN 53703
United States
Abstract Text:
NIMSTELL [1] has been developed to solve visco-resistive MHD equations in 3D configurations. The 3D geometry has been implemented by representing the physical coordinates of the finite element mesh as Fourier series in a generalized toroidal coordinate. The vector potential representation is implemented with an H(curl) basis of arbitrary polynomial degree to ensure a divergence-free magnetic field. An interface between NIMSTELL and DESC [2], a 3D ideal MHD equilibrium code, has been developed for obtaining flux-aligned finite-element grids and the corresponding equilibrium fields. Each time-advance of each of the fields V, A, n, T requires a large sparse matrix solve. Since the Fourier components of the fields are coupled in NIMSTELL’s matrices through the 3D geometry, NIMROD’s preconditioning method has been enhanced. Block-diagonal preconditioning has proven effective, where each block in the NIMSTELL implementation may include more than one Fourier component and consecutive blocks may have an overlap of modes. We present the results from preconditioning tests with multiple configurations and with different settings. NIMSTELL has been benchmarked against NIMROD for linear calculations of a (2, 1) tearing mode in a circular tokamak. Similar tearing mode calculations have been completed for a helically shaped toroidal configuration with an elliptical cross-section of eccentricity 0.8. References: [1] C. Sovinec and B. Cornille, BAPS 66(13), PP11.00092 (2021); [2] D. W. Dudt and E. Kolemen, PoP 27, 102513 (2020).
*Work supported by US DOE grants DE-SC0018642 and DE-FG02-99ER54546.
Comments: