Electromagnetic control of the instability in the liquid metal flow over a backward-facing step

Abstract

The tile-type electromagnetic actuator (TEA) and stripe-type electromagnetic actuator (SEA) are applied to the active control of the perturbation energy in the liquid metal flow over a backward-facing step (BFS). Three control strategies consisting of base flow control (BFC), linear model control (LMC) and combined model control (CMC) are considered to change the amplification rate of the perturbation energy. CMC is the combination of BFC and LMC. SEA is utilized in BFC to produce the streamwise Lorentz force thus adjusting the amplification rate via modifying the flow structures, and the magnitude of the maximum amplification rate could reach to 6 orders. TEA is used in LMC to reduce the magnitude of the amplification rate via the wall-normalwise Lorentz force, and the magnitude could be decreased by 2 orders. Both TEA and SEA are employed in CMC where the magnitude of the amplification rate could be diminished by 3 orders. In other words, the control strategy of CMC could capably alter the flow instability of the liquid metal flow.