New instability and mixing simulations using SPH and a novel mixing measure
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New instability and mixing simulations using SPH and a novel mixing measure * Georgina Reece, Benedict D. Rogers, Steven Lind, Georgios Fourtakas Department of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, UK (Received May 30, 2020, Revised June 5, 2020, Accepted June 7, 2020, Published online August 10, 2020) ©China Ship Scientific Research Center 2020 Abstract: This paper assesses the ability of smoothed particle hydrodynamics (SPH) to simulate mixing of two-phase flows and their transition to instabilities under different flow regimes. A new measure for quantification of the degree of mixing between phases in a Lagrangian framework is also developed. The method is validated using the lid-driven cavity and two-phase Poiseuille flow cases. The velocity along the centre of the cavity is compared with results from the literature, whilst commercial volume-of-fluid code STAR-CCM+ provides a benchmark for the mixing and different mixing measures are considered. The velocity of two-phase Poiseuille flow along the channel is compared to the analytical solution, and the appearance of interfacial instabilities with perturbation theory. This is the first time SPH has been used to investigate the onset and development of these instabilities. In particular, it is able to model the deforming shape of the interface, which is not given by analytical studies, while also offering improved predictions over conventional mesh-based computational fluid dynamics simulations. Key words: Smoothed particle hydrodynamics (SPH), multi-phase, mixing, instability
Introduction Numerous industrial applications involve mixing of two fluid phases. In almost all cases, it is important to know how well-mixed the product is. Yet taking a measurement at a point within the mixture can range from difficult to dangerous, as well as it being expensive to run repeated experiments until the desired confidence in the result is found. Therefore, a computational model where different experimental configurations can be tested to find out which results in the most homogeneous mixture is valuable. A computational model also gives a view of the whole domain at any time, giving an increased understanding of the physical processes which produce the resulting mixture. Mesh-based methods are regularly used to model mixing, such as the viscous multi-phase mixing models of Chang et al.[1] and Kunz et al.[2]. However, all mesh-based multi-phase methods are subject to the extra computational cost of tracking the interface. The meshless method smoothed particle hydrodynamics (SPH) offers a different approach with distinct advantages since its Lagrangian mesh-free
* Biography: Georgina Reece, Ph. D. Candidate, E-mail: [email protected] Corresponding author: Benedict D. Rogers, E-mail: [email protected]
nature allows it to naturally follow a complex, deforming interface. It can also deal with interpenetration of phases without any additional expense while also conserving important physical properties, su
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