Magnetohydrodynamic flows play an important role in the design of liquid-metal fusion reactor blankets. The interaction of the plasma-confining strong magnetic field and the electrically conducting coolant and breeding material may cause high pressure drop and unusual flow structures compared with hydrodynamic flows. In strong magnetic fields, duct flows exhibit a core where viscous effects are unimportant, while all flow variables are matched to the boundary conditions within extremely thin layers. In the inertialess inductionless limit, the governing equations can be reduced to a set of coupled two-dimensional equations for pressure and potential through analytical integration in the core and the layers. The use of curvilinear boundary-fitted coordinates leads to a unique numerical procedure for flow calculations in arbitrary geometries. The wide range of possible applications is demonstrated by some examples.