COMPUTATIONAL ANALYSIS OF FLUID FLOW AND CHEMICAL SEGREGRATION PHENOMENA IN CONTINUOUS CASTING

Continuous casting is a critical process in steel manufacturing, which yields superior quality, and efficiency compared to conventional ingot casting. However, challenges such as macro-segregation, fluid flow instabilities, and inclusion entrapment persist, directly affecting the quality and uniformity of the final steel product. This thesis presents a comprehensive computational investigation into the coupled phenomena of fluid flow and chemical segregation during continuous casting, utilizing advanced Computational Fluid Dynamics (CFD) techniques. A robust Multiphysics CFD framework was developed to model solidification, solute transport, and argon injection across full-scale slab geometries. The solidification process was simulated using the enthalpy-porosity technique, capturing the progression of mushy zones and the growth of shell thickness under realistic thermal and flow boundary conditions. A carbon segregation model, based on solute partitioning and mass transport equations, was integrated to analyze the redistribution of carbon during solidification. Parametric studies involving three different steel grades, superheat variations, and casting speeds were conducted to assess their influence on carbon segregation intensity and shell growth behavior. Additionally, the study incorporated a two-phase Euler–Lagrange model to simulate argon gas injection and its impact on mold flow dynamics. The role of bubble size and distribution was investigated in relation to flow turbulence, inclusion removal efficiency, and meniscus stability. The influence of mold geometry, particularly in thin-slab casting configurations, was also examined to understand the effects of mold width and casting speed on jet impingement, recirculation zones, and breakout risks. The simulation results revealed key insights into the mechanisms of macro-segregation, the effects of steel composition on segregation severity, and the physics of gas-liquid interactions in the mold. This work provides valuable guidelines for optimizing casting conditions to reduce centerline segregation, improve flow uniformity, and minimize surface defects. The findings offer a strong foundation for future CFD-based process control in continuous casting and contribute to the advancement of clean and high-performance steel production.