Spot turbulence, breakup, and coalescence of bubbles released from a porous plug injector into a gas-stirred ladle

Many metallurgical processes are connected with gas injection into liquid metals for refining purposes. For this reason, considerable effort has been made during the past 2 decades to investigate gas-injection operations in steelmaking ladles. Numerous physical and mathematical models are available in the literature as well as experiments (most of them performed in the air-water model). In theoretical works, usually, the bubble size is assumed constant, but this approximation is good just at low gas flow rates. When the gas flow rate increases, three different types of bubble dispersion patterns are observed in experiments. This situation cannot be predicted by means of the turbulence multiphase models normally implemented in commercial CFD codes. Their results predict a smooth (and wrong) bubble-size increase and not a sudden transition from a pattern to another, as in experiments. In this articles a new idea for approaching the bubble turbulence in the ladle, called "spot turbulence," is presented and comparison with experimental data shown.