Numerical Analysis for Interaction of Fluid and Sphere Penetrating into Liquid Bath

In the steelmaking process, it is necessary to decrease impurities in steel to meet the increasing demand for high-grade products. Top blowing and blasting of powder reagent are desirable for the purpose and the deeper penetration of particles into the bath is important for efficient refining. In the present work, CFD calculation with VOF (Volume of Fluid) method and dynamic mesh was executed to study the reported penetration and residual bubble behavior of polypropylene sphere (diameter of 9.6 mm) with a static contact angle of 87 degrees and 143 degrees and an entry solid sphere velocity of 0.63, 0.89, and 1.53 m/s in the water model experiments. Calculated results showed the numerical analysis could evaluate the formation and breakup of air column behind the sphere and the generation of consequent residual bubble on the sphere. Good wettability and high entry speed promoted the deeper penetration of the sphere. Calculated dynamic contact angle on the basis of Kistler's model indicated that the difference between static and dynamic contact angles was within 13.7 degrees in the present conditions and the discrepancy could not wield a substantial influence on the result of CFD calculation. The adoption of base and refined mesh without parallel zone around the sphere could not give a good agreement with the experimental results. On the other hand, the use of layer mesh was appropriate for reproducing the penetration depth and residual bubble volume observed in the experiments.