Towards nonaxisymmetry; initial results using the Flux Coordinate Independent method in BOUT++

TL;DR

This paper demonstrates the application of the Flux Coordinate Independent method in BOUT++ to simulate nonaxisymmetric stellarator edge transport, enabling more accurate turbulence modeling in complex geometries.

Contribution

It introduces the use of the FCI method for nonaxisymmetric transport modeling in stellarators within BOUT++, advancing turbulence simulation capabilities.

Findings

Initial nonaxisymmetric diffusion results match analytical calculations.

The FCI method effectively handles complex stellarator geometries.

Prospects for future turbulence modeling are promising.

Abstract

Fluid simulation of stellarator edge transport is difficult due to the complexities of mesh generation; the stochastic edge and strong nonaxisymmetry inhibit the use of field aligned coordinate systems. The recent implementation of the Flux Coordinate Independent method for calculating parallel derivatives in BOUT++ has allowed for more complex geometries. Here we present initial results of nonaxisymmetric diffusion modelling as a step towards stellarator turbulence modelling. We then present initial (non-turbulent) transport modelling using the FCI method and compare the results with analytical calculations. The prospects for future stellarator transport and turbulence modelling are discussed.