A new numerical model called SteelSim, which is based on the Finite Element Method (FEM), has been developed in order to investigate the Liquid Core Reduction (LCR) section in a thin slab continuous caster. As a SteelSim application example, the influence of roll alignment on temperature distribution, solidification, stress-strain distribution and strand deformation has been studied. The thermo-elasto-viscoplastic constitutive equations and the Arbitrary Lagrangian Eulerian (ALE) kinematic description for the conservation equations were calculated in the SteelSim model. From the results, it can be seen that the roll configuration: (a) symmetrical alignment of rolls with LCR, (b) asymmetrical alignment of rolls with LCR, and (c) symmetrical alignment without LCR, has an influence on the local stress-strain distribution and thus local strand deformation, which in turn affects the evolving shape profile of the narrow face. Eventually, the SteelSim model can be utilized for determining optimal roll configurations and casting conditions for specific steel grades in order to avoid the formation of critical casting defects, such as: excessive bulging, macrosegregation, cracking etc., which may lead to poor product quality or even total failure of the casting process due to a breakout. The results presented here may allow us to further analyze and validate the model with actual plant casting data.