Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
LAGRANGIAN COHERENT STRUCTURES IN NUMERICAL SIMULATIONS OF A FLUID MODEL OF TURBULENCE IN FUSION PLASMAS
Submission Author:
Ana Luiza Piragibe Freire , DF , Brazil
Co-Authors:
Rodrigo Cerda, Sarah Gomes da Silva Paes da Costa
Presenter: Ana Luiza Piragibe Freire
doi://10.26678/ABCM.COBEM2023.COB2023-2436
Abstract
We perform numerical simulations of a fluid model that describes turbulence in fusion plasmas. By changing the value of a control parameter related to adiabaticity, the numerical solutions display a transition from a turbulent regime, into a regime dominated by zonal flows, in which turbulence and radial transport is suppressed. This transition can be regarded as a low-to-high (L-H) confinement transition, in which the low confinement regime is related to the turbulent regime, and the high-confinement regime is related to the zonal flow regime. The chaotic mixing properties of the flow are characterized by means of Lagrangian coherent structures (LCS). First, we compute the finite-time Lyapunov exponent (FTLE) of the calculated velocity field derived from the electrostatic potential to better characterize the chaotic mixing of the turbulent and zona flow regimes. Then, we compare the statistics of the chaotic mixing of the two regimes using probability distribution functions (PDFs). These results can contribute to the understanding of turbulent transport processes in magnetic confinement fusion plasmas.
Keywords
Turbulence, Plasma, Finite-time Lyapunov Exponent, Lagrangian coherent structures, Chaotic mixing
