Influence of Solutal Marangoni Effect on Droplet Behavior in Metal-Slag Emulsion System: A Numerical Study

The hydrodynamic behavior of a metal droplet immersed in liquid slag because of the Marangoni effect induced by unsteady solute transfer across the slag/metal interface is simulated using the developed fluid of volume coupled with level set model. Formation and development of Marangoni convection, Marangoni convection-driven droplet deformation and breakage, and influence of Marangoni convection on droplet motion and solute transfer are investigated. Results show that the Marangoni convection presents ordered flow structure featured as several pairs of convection cells on both sides of the slag/metal interface. The critical interfacial tension at which the Marangoni convection drives severe deformation of an ellipsoid droplet is 0.26 N/m, while the droplet fractures at 0.17 N/m. As the droplet falls freely in the liquid slag, the Marangoni convective is observed and dominates the flow and solute transfer only in the early stage but then is disturbed by macroscopic relative convection which changes the ordered Marangoni convective structure. The Marangoni convective thus has an insignificant effect on solute transfer efficiency throughout the droplet falling process but retards droplet motion and results in a trajectory breakout effect of the falling droplet.