Browsing by Author "Loyseau, Xavier F."

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    Numerical simulation of droplet dispersion and deposition in pipes
    (Cranfield University, 2016) Loyseau, Xavier F.; Verdin, Patrick G.
    Multiphase flows are commonly encountered in industrial processes but remain challenging to predict. The role of droplets in the setting of various flow patterns seen in pipes is capital. Being able to simulate accurately the motion, the dispersion, the deposition and the entrainment of droplets from a liquid film or pool would allow refining the various numerical models and would provide a useful insight to people involved with such flows. The PhD work summarised in this thesis aims at answering that ambitious goal, i.e. to reproduce the whole "life" of a cloud of droplets, with application to pipes and industrial systems. To the author’s knowledge, such study has never been realized with any open source computational fluid dynamics code such as OpenFOAM and in such details. An original surface-tracking motion has also been developed to solve wavy-stratified flows and droplets entrainment by extending OpenFOAM’s capabilities. The Lagrangian framework has been selected for this study as the relationship with various forces could be expressed directly and statistical information, including any Eulerian field if needed, could be retrieved.
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    Scale-up and turbulence modelling in pipes
    (Elsevier, 2017-12-11) Loyseau, Xavier F.; Verdin, Patrick G.; Brown, L. D.
    Large diameter pipes are commonly used for oil and gas transportation. Experimental and numerical results, including turbulence properties, are often obtained for small diameter pipes. Only little information is available for pipes larger or equal to 200 mm. Results obtained with Reynolds Averaged Navier-Stokes (RANS) turbulence models for single phase flow in pipes of different sizes are presented and discussed. The use of non-dimensional data is usually assumed sufficient to present general information and is assumed valid for any size of pipe. The validity of such assumptions has been checked and the flow behaviour in small, medium and large pipes obtained with several of the most common RANS turbulence models, has been established under specific conditions via Computational Fluid Dynamics (CFD) techniques. Although difficulties were sometimes encountered to reproduce correctly the turbulence properties described in the literature with the turbulence models implemented in open source CFD codes, it is shown that a scaling-up approach is valid as the general flow pattern can be predicted by a non-dimensional strategy.
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    Statistical model of transient particle dispersion and deposition in vertical pipes
    (Elsevier, 2016-07-26) Loyseau, Xavier F.; Verdin, Patrick G.
    Water droplets in vertical pipes have been investigated to assert the accuracy of a newly developed Lagrangian model for dispersion and deposition implemented in the Open source CFD code OpenFOAM. The transient evolution of the particles dispersion and concentration has been studied for the combined effects of Brownian motion and turbulent dispersion. A parametric study of mesh density has been performed and the influence of the isotropic representation of turbulence discussed. Simulated results have been compared to experimental data from the literature and to results generated with a commercial flow solver. A new model has also been developed to predict the evolution of the droplet concentration and deposition in pipes, based on a statistical description of the dispersion.