In this study we highlight the influence of mean dilatation and mean density gradient on the Reynolds stress modeling of compressible, heat-releasing and supercritical turbulent flows.Firstly, the modeling of the rapid pressure-strain correlation has been extended to self-consistently account for the influence of mean dilatation.Secondly, an algebraic model for the turbulent density flux has been developed and coupled to the tensor equationfor Reynolds stress anisotropy via a 'local mean acceleration',a generalization of the buoyancy force. We applied the resulting differential Reynolds stress model (DRSM) and the corresponding explicit algebraic Reynolds stress model (EARSM) to homogeneously sheared and compressed or expanded two-dimensional mean flows. Both formulations have shown that our model preserves the realizability of the turbulence, meaning that the Reynolds stresses do not attain unphysical values, unlike earlier approaches. Comparison with rapid distortion theory (RDT) demonstrated that the DRSM captures the essentials of the transient behaviour of the diagonal anisotropies and gives good predictions of the turbulence kinetic energy. A general three-dimensional solution to the coupled EARSM  has been formulated. In the case of turbulent flow in de Laval nozzle we investigated the influence of compressibility effects and demonstrated that the different calibrations lead to different turbulence regimes but with retained realizability. We calibrated our EARSM against a DNS of combustion in a wall-jet flow. Correct predictions of turbulent density fluxes have been achieved and essential features of the anisotropy behaviour have been captured.The proposed calibration keeps the model free of singularities for the cases studied. In addition,  we have applied the EARSM to the investigation of supercritical carbon dioxide flow in an annulus. The model correctly captured mean enthalpy, temperature and density as well as the turbulence shear stress. Hence, we consider the model as a useful tool for the analysis of a wide range of compressible flows with large density variation. / <p>QC 20160314</p>

This report examines how games can be used to communicate and teach complex system structures. In collaboration with the total defence research institute, a game is being developed to introduce operational analysts to the Swedish total defence. The target group for the game lacked both experience in systems thinking and total defence, which is why the game was considered a good method to test. The study has a design science research approach and used Arnold and Wade's systems thinking matrix as the basis for the game's learning objectives. The development of the game is largely based on methodology taken from serious gaming, war games and game pedagogy. The result of the studies was that a number of points of interest for game development linked to complex systems are identified. Among other things, the result strengthened the idea of ​​using games as an educational tool. The study also demonstrated certain difficulties with games and complex systems, where sometimes challenges were connected to creating a game that fairly depicts even the hidden relationships within a system.