Observation of a novel flow regime caused by finite electric wall conductance in an initially turbulent magnetohydrodynamic duct flow

We present results of a series of numerical simulations of an initially fully developed turbulent flow of a liquid metal in a long duct under the influence of a constant uniform transverse magnetic field and various wall conductances (ranging from perfectly insulated to perfectly conducting walls). The changes in the wall conductance caused the appearance of novel flow regimes characterized by the coexistence of locally turbulent or laminar flow regions and a nonmonotonic behavior of the corresponding wall-friction coefficients. In contrast to the situation where an increase in the imposed magnetic field will lead to continuous suppression of turbulence and final complete relaminarization of the flow in a specific range of wall-conducting parameters, we also observe an apparent partial and complete turbulence regeneration from the magnetohydrodynamic-suppressed laminar state.