A fully compressible four-equation model for multicomponent two-phase flow coupled with a realfluid phase equilibrium-solver is suggested. It is composed of two mass, one momentum, and one energy balance equations under the mechanical and thermal equilibrium assumptions. The multicomponent characteristics in both liquid and gas phases are considered. The thermodynamic properties are computed using a composite equation of state (EoS), in which each phase follows its own Peng-Robinson (PR) EoS in its range of convexity, and the two-phase mixtures are connected with a set of algebraic equilibrium constraints. The drawback of complex speed of sound region for the two-phase mixture is avoided using this composite EoS. The phase change is computed using a phase equilibrium-solver, in which the phase stability is examined by the Tangent Plane Distance (TPD) approach; an isoenergetic-isochoric (UVn) flash including an isothermal-isobaric (TPn) flash is applied to determine the phase change. This four-equation model has been implemented into an inhouse IFP-C3D software. Extensive comparisons between the four-equation model predictions, experimental measurements in flash boiling cases, as well as available numerical results were carried out, and good agreements have been obtained. The results demonstrated that this four-equation model can simulate the phase change and capture most real-fluid behaviors for multicomponent two-phase flows. Finally, this validated model was applied to investigate the behaviors of n-dodecane/nitrogen mixtures in one-dimensional shock and double-expansion tubes. The complex wave patterns were unraveled, and the effects of dissolved nitrogen and the volume translation in PR EoS on the wave evolutions were revealed. A three-dimensional transcritical fuel injection is finally simulated to highlight the performance of the proposed four-equation model for multidimensional flows.

Microbeam facilities provide a unique opportunity to investigate the effects of ionising radiation on living biological cells with a precise control of the delivered dose. This paper describes dosimetry calculations performed at the single-cell level in the microbeam irradiation facility available at the Centre d'Etudes Nucléaires de Bordeaux-Gradignan in France, using the object-oriented Geant4 Monte Carlo simulation toolkit. The cell geometry model is based on high-resolution three-dimensional voxelised phantoms of a human keratinocyte (HaCaT) cell line. Such phantoms are built from confocal microscopy imaging and from ion beam chemical elemental analysis. Results are presented for single-cell irradiation with 3 MeV incident alpha particles.

This work aims to develop a multi-component evaporation model for droplets of urea-watersolution (UWS) and a thermal decomposition model of urea for automotive exhausts using the Selective Catalytic Reduction (SCR) systems. In the multi-component evaporation model, the influence of urea on the UWS evaporation is taken into account using a NRTL activity model. The thermal decomposition model is based on a semi-detailed kinetic scheme accounting not only for the production of ammonia (NH 3 ) and isocyanic acid (HNCO), but also for the formation of heavier solid by-products (biuret, cyanuric acid and ammelide). This kinetics model has been validated against gaseous data as well as solid-phase concentration profiles obtained by Lundstroem et al. (2009) andSchaber et al. (2004). Both models have been implemented in IFP-C3D industrial software in order to simulate UWS droplet evaporation and decomposition as well as the formation of solid by-products. It has been shown that the presence of the urea solute has a small influence on the water evaporation rate, but its effect on the UWS temperature is significant. In addition, the contributions of hydrolysis and thermolysis to urea decomposition have been assessed. Finally, the impacts of the heating rate as well as gas-phase chemistry on urea decomposition pathways have been studied in detail. It has been shown that reducing the heating rate of the UWS causes the extent of the polymerization to decrease because of the higher activation energy.