Iranian Journal of Chemical Engineering (IJChE)

Abstract In this paper, drag coefficient of infinite quadralobe catalytic particle with non-circular cross sections has been investigated by Computational Fluid Dynamics (CFD) methods and for this purpose FEMLAB Multiphysics V2.3 based on finite element methods have been used. A new simple correlation for drag coefficient of infinite quadralobe particle
has been established over the range of Reynolds numbers from 0.01 up to 1000. A comparative study has been made between the numerical results of this study and the available data in the literature. The predicted drag coefficient of infinite cylinder shows good agreement with experimental data within a converging quantitative error of less than 7% up to Reynolds number of 1000. The drag coefficient results for cross flow on infinite quadralobe particle shows higher value in comparison with cylindrical particle. In addition, influence of different number of particles (single, two, three and four particles) and orientation angle of particles on drag coefficient have been investigated.

Abstract Secondary breakup of Newtonian droplet into continuous air jet was numerically studied. A coupled Large Eddy Simulation (LES)/ Volume of Fluid (VOF) technique was used in this investigation. Dynamic adaptive mesh was also employed. To this end, the open source CFD package, OpenFOAM, was used to perform the numerical study and was modified to meet the needs of the problem. In order to reduce the error, resulting from the spurious currents, Laplacian smoothing filter was used, which transforms the volume fraction into a smoother volume fraction. This filtering process also helped to obtain a sharp fluid interface. The smoothing has qualitatively and quantitatively improved the simulation results in bag breakup regime. Comparing the results of the RNG k-ε turbulence model and LES model showed the great influence of LES model to improve results. The detailed physics of two different breakup regimes, i.e. bag and multimode (streamer) were investigated. The numerical drop breakup regimes showed appropriate agreement with experimental observation. According to the analogy between the secondary and primary atomization, the outcomes can be used for development of the atomization models.

Abstract In this paper, the droplet size distribution of the Tehran refinery crude oil/water emulsions is determined by analyzing the photomicrographs of model emulsions which were taken by microscope. The normal distribution function is fitted to the
experimental data in order to reproduce the droplet size distribution (DSD) of the emulsions by using mean diameter and standard deviation. The effect of different parameters such as surfactant concentration, salinity, and the power of homogenizer on the droplet size distribution and mean droplet diameter of the emulsions are determined. The smaller droplet size was observed in high concentrations of surfactant and in the absence of salt, and also in emulsions which were prepared with lower power of homogenizer.