Numerical study of two-phase phenomena using OpenFOAM

Jameel, Atheel 2017. Numerical study of two-phase phenomena using OpenFOAM. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

An Open source “OpenFOAM” CFD modelling tool and multi-phase solvers are used to solve two-phase flow problems of relevance a variety of engineering applications. Validation of several benchmark two-phase model predictions is presented and discussed. For the different cases considered, the comparison showed that this CFD simulation tool is suitable for modelling multi-phase problems. Furthermore, the comparison revealed that the sclsVOFFoam (LS+VOF) solver is more accurate than interFoam (VOF) and showed better agreement with previous studies. Hence, it is concluded that OpenFOAM with the sclsVOFFoam (VOF+LS) solver is suitable for simulation of multi-phase problems, and so is chosen for implementation in this research study. Numerical studies of two multi-phase problems of practical significance are studied in detail, namely: (i) the coalescence of two droplets and (ii) the jet-burst phenomena of a high speed laminar jet. The numerical framework (geometrical, computational and physical settings) for the two problems are constructed and validated against relevant studies from literature. For the interaction of two droplets problem, numerical results are obtained for the flow phenomena to investigate the final composite droplet location at different lateral separation, impact speed and liquid properties (viscosity and surface tension). It is found that the composite droplet location (centre-of-mass ) relative to the initial condition (initial centre-of-mass) is influenced significantly by the impacting droplet velocity and liquid properties, but showed the same non-intuitive final location displacement for the three overlap ratios (lateral separation) studied in this research. For the high speed laminar jet problem, at ReL=2200, results are obtained for different inflow velocity profile, ambient gas viscosity and reduced liquid viscosity. From the results for the high speed laminar liquid jet, it is concluded that this is predominantly a laminar phenomenon, where the inlet velocity profile plays a critical role in determining burst onset. Secondary flow due to the axial velocity relaxation is found to be influential in determining the onset of the jet burst. Also, the results demonstrate that aerodynamic effects play a minimal role in influencing liquid jet burst characteristics. These results are useful in informing estimates of jet breakup length in practical problems, such as (explosive) area classification for accidental releases of high-flashpoint fuels.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Burst of laminar Jet; Fluid properties effect; Two Droplets; Composite Location; OpenFOAM; VOF+LS.
Date of First Compliant Deposit:	18 December 2017
Last Modified:	18 May 2021 09:22
URI:	https://orca.cardiff.ac.uk/id/eprint/107592

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