Simulation of Slag Droplet Entrainment by Volume of Fluid and Lagrangian Particle Tracking Coupled Modeling

The slag dropletentrainment is a common phenomenon in steel refiningprocesses, which may lead to inclusions and defects. In the multiphaseflow system, the distinct interface and tiny blobs possess a widerange of spatial and temporal scales and make it hard to be simulated.In numerical methods, the volume of fluid (VOF) approach is appropriatefor capturing the interface, but for the unresolvable tiny blobs,the Lagrangian particle tracking (LPT) is preferable. This work newlyimplements a bidirectional VOF-LPT transformation algorithmfor developing a multiscale solver in OpenFOAM to simulate the slagdroplet entrainment. The interIsoFoam solver is selected as the mainsolver to resolve the interface, and the resolution is improved withusing the geometric reconstruction and the adaptive mesh refinement(AMR). For capturing tiny droplets, a connected component labeling(CCL) method is adopted for detecting discrete droplets in the VOFfield, and then the VOF-to-LPT transition takes place for saving computationalcosts. Conversely, the LPT-to-VOF transformation for droplets touchingthe interface is also incorporated to achieve the bidirectional transition.The solver is first validated by a simple case, indicating that thetwo-way transition algorithm and the Eulerian-Lagrangian momentumcoupling are accurate. Then the solver is applied to simulate theslag layer behavior for revealing the mechanisms of slag droplet formationand entrainment. Two main mechanisms of slag droplet formation areidentified, and it is found that fewer discrete droplets are generatedwhen the surface tension increases.

Automated summary

Slag droplet entrainment is a common issue in steel refining processes, but it is difficult to simulate due to the complex nature of the multiphase flow system. In this study, a bidirectional VOF-LPT transformation algorithm was developed to simulate the entrainment process. The algorithm successfully captured the interface using the VOF approach and tracked tiny droplets using the LPT method, providing accurate results. The solver was validated and applied to investigate the mechanisms of slag droplet formation and entrainment.