The buoyancy-driven magnetoconvection in the cross
section of an infinitely long vertical square duct is investigated
numerically using the CFX code package. The
implementation of a magnetohydrodynamic (MHD) problem
in CFX is discussed, with particular reference to the
Lorentz forces and the electric potential boundary conditions
for arbitrary electrical conductivity of the walls.
The method proposed is general and applies to arbitrary
geometries with an arbitrary orientation of the magnetic
field. Results for fully developed flow under various thermal
boundary conditions are compared with asymptotic
analytical solutions. The comparison shows that the asymptotic
analysis is confirmed for highly conducting walls
as high velocity jets occur at the side walls. For weakly
conducting walls, the side layers become more conducting
than the side walls, and strong electric currents flow
within these layers parallel to the magnetic field. As a
consequence, the velocity jets are suppressed, and the core
solution is only corrected by the viscous forces near the
wall. The implementation of MHD in CFX is achieved