Numerical simulations of MHD flows in a conduit that contracts in the magnetic field direction

Abstract The present study numerically concerns 3D simulations of LM MHD flow moving through a conducting conduit with sudden and gradual contraction exposed to an external magnetic field. The results display that the LM MHD flow in a contraction conduit induces unique flow field in association with the electromagnetic effect therein, yielding a large-scaled electric circuit passing through the front-facing wall and fluid domain around the contraction segment. Besides, cases with different contraction ratios for sudden contraction and with different contraction angles for gradual contraction in the contracting conduit flows are considered, and the change of the pressure gradients in different cases is discussed and compared with a previous analytic solution. Flow patterns in the contraction segment are also presented in detail in sudden and gradual contractions. A small local velocity vortex is formed in fluid area around the leading edge of the downstream channel in the sudden contraction, while smooth streamlines are formed in the contraction segment in the gradual contraction.