Magnetohydrodynamic flow in ferromagnetic pipes

The major part of the magnetohydrodynamic pressure drop in the European water cooled concept for a fusion blanket arises in circular pipes which distribute the liquid metal breeder among the poloidal containers. These channels are surrounded by a massive structure of electrically conducting ferromagnetic material. This structure acts like a magnetic shielding for moderate external magnetic fields and reduces pressure drop. For fusion relevant conditions the magnetic shielding is not perfect since the wall material reaches magnetic saturation. The most interesting regime exists near magnetic saturation where curvilinear field lines inside the pipe are observed. They result in velocity profiles, which differ from the well known classical solutions.