Numerical Simulation of Heat Transfer and Steel Shell Growth in a Curved Slab Mold

The main aims of the present research is the study of steel flow under temperature gradient to understand the convective effects on the flow patterns inside the mold and its effects on the shell growth kinetics under more realistic conditions. In order to achieve this, a non-isothermal mathematical model is developed based on the Navier-Stokes equations together with the k-epsilon turbulence model, the volume of fluid model to solve the multiphase system air-slag-steel and a solidification model. Comparing isothermal and non-isothermal results, it is observed that the buoyancy forces are large enough to modify radically the lower recirculation flows inducing shorter and upwards streams; however, the upper recirculation flows do not show strong changes. Shell growth does not necessarily follow a steady parabolic growth and it is more dependent on the washing effects of convective steel streams. Therefore, shell thickness reports heterogeneous and irregular magnitudes through the four faces of the slab. In addition, mold curvature provides uneven shell growth in the inner side of the slab while in the outer side the shell thickness observes a more regular growth. Shell thickness is irregular and discontinuous all around the upper periphery of the slab; therefore, this region is very sensitive to cracking. Finally, the numerical results for liquid steel solidification are compared to published results of shell growth showing a very good qualitative agreement.