A quantitative study of the axial and tangential components of the mean velocity in a 3"-hydrocyclone using laser doppler anemometry has revealed multiple reverse flows in the vortex core . Flow visualization by dye injection shows that these flows are coherent over a significant portion of the hydrocyclone and that little radial mixing occurs between these secondary flows and the outer helical flow. A 2: 1 contraction in the vortex finder plays an important role in causing four distinct simultaneous countercurrent flows in the conical section of the hydrocyclone.

An improved mathematical model for falling film reactors is presented. Effects of liquid film turbulence, gas phase heat and mass transfer resistances, gas-liquid interfacial drag, exothermic chemical reaction and heat transfer within the system, as well as volatility of liquid film are considered. The model predicts liquid phase chemical conversions and the interracial temperatures along the reactor length. Model predictions agreed well with data from both laboratory and industrial scale reactors.

Immiscible liquid dispersions are widely used in chemical process, petroleum industries, polymerization, heterogeneous chemical synthesis, etc. In most of these chemical processes, the rate of inter-phase heat and mass transfer is known to strongly affect the overall performance and depends on the interfacial contact area between the phases. This study at CFD simulations of immiscible liquid dispersion has been performed on a vertical pipe. With specific reference to dispersed liquid-liquid flows, it was seen that the two-fluid approach (Eulerian-Eulerian approach) was extensively used for multiphase modeling, especially when detailed predictions are desirable over a range of holdups in exchange for a reasonable amount of computation power. The results of CFD predictions for water as a continuous and kerosene as a dispersed phase have been compared with the experiments of Farrar and Bruun and Al-Deen and Bruun. These simulations have also been done to understand the effect of various significant forces in turbulent liquid dispersions (drag, lift, turbulent dispersion and added mass). Several expressions for these forces were tested in order to choose the best combination. Further, the problem has been simulated using two different turbulence models. It has been found that lift force is more important than turbulent dispersion and added mass. Inter-phase closure guidelines for liquid-liquid bubbly flows were developed based on simulation results that yielded the best agreement with experimental data.

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Fine grid geocellular reservoir characterizations often include detailed description of geological and geometric complexity. Since this volume of details cannot be handled by commercial reservoir simulators, some degree of coarsening is necessary. The fundamental agenda in coarse grid generation includes development of finer grids in regions with higher flow. Available methods in literature suffer from draw back of inability to consider both the well and geological features which mostly affect the flow response. This study introduces a new method of grid coarsening (flow based) procedure. The procedure encompasses tracing streamline from boundary to the well, monitoring velocity trend along streamline to identify high flow region and selection of appropriate points on streamlines as grid nodes. Differentiating the analytical equation of the streamline path results in developing velocity vectors and adding them up will yield a new term called cumulative velocity. Using this term, the grid points are easily identified which after implementation of Delaunay triangulation and Laplacian smoothing algorithms the main CVFE (Control Volume Finite Element) grid is produced. In addition, a robust up-scaling technique was used to calculate the tensor of permeability. Flux-continuous finite volume scheme was used to solve the associated flow equation in the coarse block. The generated grid pattern is finer in high flow regions and can successfully adapt itself based on type of geological features presented. Pressure was the main criteria for comparison the results of this study with those of Cartesian coarse grid. The results indicated that the response of the model with coarse grids (flow based) is more consistent with a fine model. The major advantage of the introduced method is its capability in handling the geological features within the grid. It is worthy to mention that the positioning of the well and adjustment of the required refinements around it are done automatically. Introduction Reservoir simulation is an important tool for the management of oil fields. Geological characterization and equations governing flow through porous media is used to simulate reservoir flow numerically. But where to consider geological variations and how much detail to consider when dealing with them, are questions that challenge engineers. During the process of griding and discritization physical properties are assigned to each grid block. Concentration of grid blocks represents the degree of detail we have considered and its location in the domain shows where geological variations have more importance. This indicates that grid generation method plays an important role when regarding number of grid produced. Geological models contain as much as grid blocks that cannot be handled by commercial reservoir simulators software due to computational cost. These models are called fine grid models or geostatistical models which contain fine scale geological variation. In order to reduce the number of blocks we should use coarser blocks. But petrophysical properties like permeability are defined in fine grid model. There should be a process to assign fine grid properties to the coarse grid. This process is called upscaling. In the process of griding and upscaling the tendency is to preserve critical reservoir features as much as possible. In this paper, we tried to take into account this fact by concentrating grid nodes in important regions to capture reservoir features. Different attempts have been performed so far in this area. The first one was the idea of local grid refinement (Ciment and sweet 1973; Pedrosa and Aziz 1985). Local grid refinement involves using fine grid inside coarse base grid. This is done in selected regions like near well regions or highly heterogeneous regions.

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A Computational Fluid Dynamics (CFD) model of two phase flow is presented to simulate isothermal, turbulent, upward bubbly flows in a pipeline till forecast a mean pressure reduction along the pipe (a 3 dimensional (3D) multiphase flow, by Eulerian-Eulerian strategy combined with Population Balance Modeling (PBM)). A set of experimental data from the literature for water (liquid) and air (gas) in an isothermal pipe is used where the internal diameter of which is 200 mm, employed in order to analyze radial void fraction and bubble diameter distributions as well as the axial pressure distribution of fluid flow. The CFD model is applied to grids of minimum control volumes. The interfacial forces, including non-drag and drag forces, where the former can be categorized into turbulent scattering, lift, and wall lubrication, have been noticed in following simulations. The comparison between CFD forecasts with empirical data demonstrates that the coring phenomena plus observed wall peaking could be predicted with this CFD-PBM modeling approach. The primary intention of this work was to anticipate the axial pressure distribution of bubbly flow in the pipe by CFD modeling in a large vertical pipe. Acceptable agreement between predicted models and experimental data indicates that CFD can be a beneficial method for investigating pressure drop of an upward and multi-phase flow.

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