TY - JOUR

T1 - Accelerating the solution of a physics model inside a tokamak using the (Inverse) Column Updating Method

AU - Haelterman, R.

AU - Van Eester, D.

AU - Verleyen, D.

N1 - Publisher Copyright:
© 2014 Elsevier B.V. All rights reserved.

PY - 2015/5/1

Y1 - 2015/5/1

N2 - Many physics problems can only be studied by coupling various numerical codes, each modeling a subaspect of the physics problem that is addressed. In most cases, the "brute force" technique of running the codes one after the other in a loop until convergence is reached requires excessive CPU time. The present paper illustrates that re-writing the coupling as a root-finding problem, to which a quasi-Newton method-here the (Inverse) Column Updating Method-can be applied, is useful to push down the computation time, at the expense of a very modest amount of supplementary programming. A simplified version of the set of codes commonly used to describe plasma heating by radio frequency waves in a tokamak plasma is adopted for illustrating the potential of the speed-up method. It consists of a wave equation as well as a Fokker-Planck velocity space diffusion and a radial energy diffusion model. It is shown that with this approach a substantial reduction in CPU time needed for convergence can be obtained.

AB - Many physics problems can only be studied by coupling various numerical codes, each modeling a subaspect of the physics problem that is addressed. In most cases, the "brute force" technique of running the codes one after the other in a loop until convergence is reached requires excessive CPU time. The present paper illustrates that re-writing the coupling as a root-finding problem, to which a quasi-Newton method-here the (Inverse) Column Updating Method-can be applied, is useful to push down the computation time, at the expense of a very modest amount of supplementary programming. A simplified version of the set of codes commonly used to describe plasma heating by radio frequency waves in a tokamak plasma is adopted for illustrating the potential of the speed-up method. It consists of a wave equation as well as a Fokker-Planck velocity space diffusion and a radial energy diffusion model. It is shown that with this approach a substantial reduction in CPU time needed for convergence can be obtained.

KW - Column Updating Method

KW - Integrated tokamak modeling

KW - Iterative method

KW - Quasi-Newton method

UR - http://www.scopus.com/inward/record.url?scp=84912551823&partnerID=8YFLogxK

U2 - 10.1016/j.cam.2014.11.005

DO - 10.1016/j.cam.2014.11.005

M3 - Article

AN - SCOPUS:84912551823

SN - 0377-0427

VL - 279

SP - 133

EP - 144

JO - Journal of Computational and Applied Mathematics

JF - Journal of Computational and Applied Mathematics

ER -