Numerical simulation of electrically conducting jet flow in a straight duct under longitudinal homogeneous magnetic field

Spatial evolution of electrically conducting jet flow at a supercritical Reynolds number, entering a duct filled with the liquid of the same physical properties, is studied by direct numerical simulations for the case of a streamwise uniform magnetic field. In contrast to the case of a transverse field, here the jet mean velocity does not interact with the streamwise field, and only the turbulent fluctuations of the flow are influenced and suppressed by the field. In this case, the jet saves its energy and has a tendency to spread at much larger distances. Therefore, one interesting and important property of this setup is the flow stabilization, i.e., transition to turbulence can be largely delayed due to the stabilizing effect of the magnetic field. This occurs in the presence of moderate magnetic fields. At strong magnetic fields, the second instability evolves—the jet profile becomes unsteady due to the traveling waves, which propagate along the jet while not interacting with the field. These traveling waves are generated by the interaction of secondary radial flows and magnetic field.