Abstract of ZOFLIN Project

The project targets the nonlinear dynamics of zonal flows and geodesic acoustic modes by systematically determining the nonlinear functional governing the turbulence forces on the flows, the influence of the inhomogeneous situation in the high gradient edge and of varying geometry. An advantage of this novel method is that from its results metastable states of turbulence and flows can be inferred, even if they are not easily accessible upon starting from the ground state of the turbulence. To determine the stress response functional requires significantly larger computational resources than just the transport level, whence this problem is ideally suited for HPC-FF. Apart from gyrokinetic codes, the nonlocal electromagnetic threedimensional two-fluid code NLET is used for the major part of these studies. It is proposed to optimise the code to potentially gain about 50% in efficiency and to implement parallel visualisation capabilities to allow real time diagnostics during runs and facilitate fast turn around time in the result analysis.