1 A Partitioned Fluid-Structure Interaction Approach during Steel Solidification: Application to the simulation of Ingot Casting

One of the critical challenges encountered when modeling a thermo-mechanical problem in the context of steel casting processes, is to achieve a concurrent and efficient computation of fluid flow (ingot mould filling, nozzle jet in continuous casting) and solid mechanics (stress-strain in solidified regions). This is of crucial importance in industry for the prediction of surface or sub-surface cracks for instance that may initiate in solidified regions during the filling stage of ingot casting, or in the mould region during continuous casting. The current state-of-the-art [15-17-21] consists in separating the analysis in two distinct stages: fluid flow using CFD codes and stress-strain analysis using structural codes. This induces several drawbacks regarding practical use and computational efficiency. A monolithic formulation, treating the fluid-solid interaction (FSI) may be investigated but is not adapted to the context of solidification, because of huge differences between liquid viscosity and solid consistency. It is then preferable to consider this FSI problem as a weak interaction problem, for which a partitioned formulation is more efficient than a monolithic one. Therefore, a two-step resolution strategy combining fluid flow and solid mechanics has been developed. Liquid flow (natural convection or filling flow), thermal dilatation as well as thermally induced deformation of the solid phase are accounted for