Comparison of Different Techniques for the Treatment of the Electromagnetic Field for Studying Inductively-Coupled Plasma Torches by means of the Fluent Code

FLUENT offers important advantages in the modelling of ICPTs, such as the reliability of employing a well-tested code and the possibility of studying complicated geometries. The difficulty due to the lack of a module for electromagnetic (EM) calculations can be overcome following two ways: 1) using the FLUENT solver for two new scalar quantities (the complex electric field or the vector potential as in [1]); 2) solving the EM eqs. outside FLUENT while limiting the fluiddynamics domain to the torch region. The first option, using entirely FLUENT, requires a computational domain much larger than the torch and particular care must be used to impose the correct boundary conditions for the fluid-dynamics eqs. The second way, in principle more computationally efficient, requires the user to develop a C-function to solve the EM field eqs. In the present work, the Magnetic Dipole Boundary Condition (MDBC) for the EM field [2-3], is introduced in FLUENT following both ways. MDBC, although approximate, is more precise with respect to simply impose the field to vanish, as proposed in [1]. Results are presented for various configurations, showing temperature, velocity and EM fields, and compared with those obtained with a finite-volume code. Grid optimisation and accurate modelling of the coil region is discussed.