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In this work we propose to study the behavior of a solid elastic object that interacts with a multiphase flow. Fluid structure interaction and multiphase problems are of great interest in engineering and science because of many potential applications. The study of this interaction by coupling a fluid structure interaction (FSI) solver with a multiphase problem could open a large range of possibilities in the investigation of realistic problems. We use a FSI solver based on a monolithic approach, while the two-phase interface advection and reconstruction is computed in the framework of a Volume of Fluid method which is one of the more popular algorithms for two-phase flow problems. The coupling between the FSI and VOF algorithm is efficiently handled with the use of MEDMEM libraries implemented in the computational platform Salome. The numerical results of a dam break problem over a deformable solid are reported in order to show the robustness and stability of this numerical approach. [ABSTRACT FROM AUTHOR]

Computational Fluid Dynamics codes are used in many industrial applications in order to evaluate interesting physical quantities, such as the heat transfer in turbulent flows. Commercial CFD codes use only turbulence models with an imposed constant turbulent Prandtl number Prt, which can give accurate results only for simulations when a strong similarity between the velocity field and the temperature field can be assumed. For fluids with a low Prandtl number, as for heavy liquid metals, a constant turbulent Prandtl number leads to an overestimation of the heat transfer, so experimental results and Direct Numerical Simulation cannot be reproduced. In this work we propose a new k-Ω-kθ-Ωθ turbulence model as an improvement of the k-ω-kθ-ωθ turbulence model, already validated by the authors, where Ω and Ωθ are calculated as the natural logarithm of the variables ω and ωθ. With this reformulation of the previous turbulence model we obtain some important advantages in numerical stability and robustness of the code. Results for the simulations of fully developed turbulent flows in two and three dimensional geometries are reported and compared with experimental correlations and DNS data, when available. [ABSTRACT FROM AUTHOR]

In this work we propose a preliminary model to study the deformation of solid structures induced by the interaction with a two-phase flow. The study of Fluid Structure Interaction and multiphase problems is of great interest because of many potential applications ranging from the biomedical field to the pressure tank design. We use a monolithic approach for the FSI problem while a Volume Of Fluid method (VOF) is considered for the reconstruction and the advection of the multiphase interface. An unstructured, time dependent computational grid and a fine Cartesian mesh are used for the FSI and the VOF problem, respectively. The interaction between the two different grids is obtained by projecting the velocity and the displacement field into the Cartesian grid and the color function into the unstructured mesh. This projection is performed with the MEDmem libraries included in the Salome platform. Concerning the VOF method, for an accurate reconstruction of the interface a huge number of computational elements are required and a multilevel algorithm coupled to an efficient compression-expansion technique is developed to reduce computational costs and memory requirements. After the mathematical description of the problems we test the proposed algorithm with different cases where the solid domain undergoes to both small and large deformation. [ABSTRACT FROM AUTHOR]

An overview of existing split and unsplit Volume-of-Fluid transport algorithms is presented. The emphasis is set on establishing a parallel between both types of algorithms, and their performance regarding accuracy and mass conservation. [ABSTRACT FROM AUTHOR]