Simulation results are presented from a finite element calculation of transport in the edge and divertor of TdeV. In addition to the usual transport processes, this model also includes a calculation of the electrostatic potential and the associated E*B drifts. The inclusion of E*B drifts is shown to be essential in the calculation of the parallel and toroidal flow velocities. With the inclusion of drifts, the effect of toroidal magnetic field reversal is studied, particularly with regard to in-out asymmetries in the Halpha radiation and power deposited on the plates. Relatively weak asymmetries are calculated on the basis of these drifts alone, and it is concluded that the much stronger asymmetries observed experimentally must be associated with other physical processes not yet included in the model. The transport equations are based on fluid conservation equations for particles, parallel (to the magnetic field) momentum, electron and ion energy. For simplicity, a single ion species is considered and, when modelling recycling, neutral transport is treated in the diffusion approximation. All transport equations are discretized with finite elements on a triangular unstructured mesh that is locally aligned with the flux surfaces. The use of such a mesh allows an accurate representation of the simulation geometry, with boundaries of arbitrary shapes and complexity. In particular, it is possible to account for divertor plates that are not orthogonal to the flux surfaces without any penalty for the validity of the transport equations. The analysis presented here concerns a low density attached ohmic TdeV discharge in a single null geometry, with the X point above the midplane
Three-dimensional computation of collisional drift wave turbulence and transport in tokamak geometry