ParMooN is a program package for the numerical solution of elliptic and parabolic partial differential equations. It inherits the distinct features of its predecessor MooNMD [28]: strict decoupling of geometry and finite element spaces, implementation of mapped finite elements as their definition can be found in textbooks, and a geometric multigrid preconditioner with the option to use different finite element spaces on different levels of the multigrid hierar- * Corresponding author.Email addresses: ulrich.wilbrandt@wias-berlin.de (Ulrich Wilbrandt), clemens.bartsch@wias-berlin.de (Clemens Bartsch), naveed.ahmed@wias-berlin.de (Naveed Ahmed), najib.alia@wias-berlin.de (Najib Alia), felix.anker@wias-berlin.de (Felix Anker), laura.blank@wias-berlin.de (Laura Blank), alfonso.caiazzo@wias-berlin.de (Alfonso Caiazzo), sashi@cds.iisc.ac.in (Sashikumaar Ganesan), swetlana.giere@wias-berlin.de (Swetlana Giere), gunar.matthies@tu-dresden.de (Gunar Matthies), raviteja@cmg.cds.iisc.ac.in (Raviteja Meesala), shamim@cmg.cds.iisc.ac.in (Abdus Shamim), jagan@cmg.cds.iisc.ac.in (Jagannath Venkatesan), volker.john@wias-berlin.de (Volker John)1 The work of Najib Alia has been supported by a funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk lodowska-Curie grant agreement No. 675715 (MIMESIS).2 The work of Felix Anker has been supported by grant Jo329/10-2 within the DFG priority programme 1679: Dynamic simulation of interconnected solids processes.3 The work of Sashikumaar Ganesan has partially been supported by the Naval Research Board, DRDO, India through the grant NRB/4003/PG/368. 4 The work of Volker John has partially been supported by grant Jo329/10-2 within the DFG priority programme 1679: Dynamic simulation of interconnected solids processes. chy. After having presented some thoughts about in-house research codes, this paper focuses on aspects of the parallelization for a distributed memory environment, which is the main novelty of ParMooN. Numerical studies, performed on compute servers, assess the efficiency of the parallelized geometric multigrid preconditioner in comparison with some parallel solvers that are available in the library PETSc. The results of these studies give a first indication whether the cumbersome implementation of the parallelized geometric multigrid method was worthwhile or not.

During ladle stirring, a gas is injected into the steel bath to generate a mixing of the liquid steel. The optimal process control requires a reliable measurement of the stirring intensity, for which the induced ladle wall vibrations have proved to be a potential indicator. An experimental cold water ladle with two eccentric nozzles and eight mono-axial accelerometers was thus investigated to measure the vibrations. The effect of the sensors' positions with respect to the gas plugs on the vibration intensity was analyzed, and experimental data on several points of the ladle were collected for future numerical simulations. It is shown that the vibration root-mean-square values depend not only on process parameters, such as gas flow rate, water, and oil heights, but also on the radial and axial positions of the sensors. The vibration intensity is clearly higher, close to the gas plumes, than in the opposite side. If one of the nozzles is clogged, the vibration intensity close to the clogged nozzle drops drastically (À 36 to À 59%), while the vibrations close to the normal operating nozzle are hardly affected. Based on these results, guidelines are provided for an optimized vibration-based stirring.

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Ladle stirring is an important step of the steelmaking process to homogenize the temperature and the chemical composition of the liquid steel and to remove inclusions before casting. Gas is injected from the bottom of the bath to induce a turbulent flow of the liquid steel. Multiphase modeling of ladle stirring can become computationally expensive, especially when used within optimal flow control problems. This paper focuses therefore on single-phase flow models. It aims at improving the existing models from the literature. Simulations in a 2d axial-symmetrical configuration, as well as, in a real 3d laboratory-scale ladle, are performed. The results obtained with the present model are in a relative good agreement with experimental data and suggest that it can be used as an efficient model in optimal flow control problems.