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Author

A-Man Zhang

Other affiliations: University College London
Bio: A-Man Zhang is an academic researcher from Harbin Engineering University. The author has contributed to research in topics: Bubble & Jet (fluid). The author has an hindex of 34, co-authored 177 publications receiving 3758 citations. Previous affiliations of A-Man Zhang include University College London.


Papers
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TL;DR: In this article, a particle shifting technique is used to improve the δ + -SPH model and a special treatment has been developed for particles that are close to the free surface region.

213 citations

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TL;DR: In this paper, a multiphase Smoothed Particle Hydrodynamics (SPH) method is applied to simulate the phenomena of bubbles rising and coalescing in three dimensions.

155 citations

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TL;DR: An improved 3D bubble dynamics model based on Boundary Element Method demonstrates good accuracy and stability, and more toroidal bubble evolution detailed features are captured which are in accordance with the axisymmetric model.

150 citations

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TL;DR: A review of the recent developments of smoothed particle hydrodynamics (SPH) method and its typical applications in fluid-structure interactions in ocean engineering can be found in this article.
Abstract: In ocean engineering, the applications are usually related to a free surface which brings so many interesting physical phenomena (e.g. water waves, impacts, splashing jets, etc.). To model these complex free surface flows is a tough and challenging task for most computational fluid dynamics (CFD) solvers which work in the Eulerian framework. As a Lagrangian and meshless method, smoothed particle hydrodynamics (SPH) offers a convenient tracking for different complex boundaries and a straightforward satisfaction for different boundary conditions. Therefore SPH is robust in modeling complex hydrodynamic problems characterized by free surface boundaries, multiphase interfaces or material discontinuities. Along with the rapid development of the SPH theory, related numerical techniques and high-performance computing technologies, SPH has not only attracted much attention in the academic community, but also gradually gained wide applications in industrial circles. This paper is dedicated to a review of the recent developments of SPH method and its typical applications in fluid-structure interactions in ocean engineering. Different numerical techniques for improving numerical accuracy, satisfying different boundary conditions, improving computational efficiency, suppressing pressure fluctuations and preventing the tensile instability, etc., are introduced. In the numerical results, various typical fluid-structure interaction problems or multiphase problems in ocean engineering are described, modeled and validated. The prospective developments of SPH in ocean engineering are also discussed.

145 citations

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TL;DR: In this paper, the dynamics of large bubbles subject to various strengths of buoyancy effects, which are associated with applications for underwater explosion, are investigated. But the results are limited to the case where the bubbles recorded are transparent, and thus they are able to display and study the jet formation, development and impact on the opposite bubble surface.
Abstract: This paper is concerned with the dynamics of large bubbles subject to various strengths of buoyancy effects, which are associated with applications for underwater explosion. The bubble is produced by electric discharge in a low-pressure tank to enhance the buoyancy effects. Experiments are carried out for a bubble in an infinite field, below a free surface and above a rigid boundary. The effects of buoyancy are reflected by the dimensionless parameter , where , , , and are the maximum bubble radius, ambient pressure, saturated vapour pressure, density of water and the acceleration of gravity respectively. A systematic study of buoyancy effects is carried out for a wide range of from 0.034 to 0.95. A series of new phenomena and new features is observed. The bubbles recorded are transparent, and thus we are able to display and study the jet formation, development and impact on the opposite bubble surface as well as the subsequent collapsing and rebounding of the ring bubble. Qualitative analyses are carried out for the bubble migration, jet velocity and jet initiation time, etc. for different values of . When a bubble oscillates below a free surface or above a rigid boundary, the Bjerknes force due to the free surface (or rigid boundary) and the buoyancy are in opposite directions. Three situations are studied for each of the two configurations: (i) the Bjerknes force being dominant, (ii) the buoyancy force being dominant and (iii) the two forces being approximately balanced. For case (iii), we further consider two subcases, where both the balanced Bjerknes and buoyancy forces are weak or strong. When the Bjerknes and buoyancy forces are approximately balanced over the pulsation, some representative bubble behaviours are observed: the bubble near free surface is found to split into two parts jetting away from each other for small , or involutes from both top and bottom for large . A bubble above a rigid wall is found to be subject to contraction from the lateral part leading to bubble splitting. New criteria are established based on experimental results for neutral collapses where there is no dominant jetting along one direction, which correlate well with the criteria of Blake et al. (J. Fluid Mech., vol. 170, 1986, pp. 479–497; J. Fluid Mech., vol. 181, 1987, pp. 197–212) but agree better with the experimental and computational results.

140 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors assess the recent trends in the numerical meshless method smoothed particle hydrodynamics, with particular focus on its potential use in modelling free-surface flows.
Abstract: This paper assesses some recent trends in the novel numerical meshless method smoothed particle hydrodynamics, with particular focus on its potential use in modelling free-surface flows. Due to its Lagrangian nature, smoothed particle hydrodynamics (SPH) appears to be effective in solving diverse fluid-dynamic problems with highly nonlinear deformation such as wave breaking and impact, multi-phase mixing processes, jet impact, sloshing, flooding and tsunami inundation, and fluid–structure interactions. The paper considers the key areas of rapid progress and development, including the numerical formulations, SPH operators, remedies to problems within the classical formulations, novel methodologies to improve the stability and robustness of the method, boundary conditions, multi-fluid approaches, particle adaptivity, and hardware acceleration. The key ongoing challenges in SPH that must be addressed by academic research and industrial users are identified and discussed. Finally, a roadmap is propose...

326 citations

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TL;DR: In this article, the authors summarize the motivations behind utilizing the smoothed particle hydrodynamics (SPH) method in an industrial context, as well as deriving general conclusions regarding its assets and limitations and stressing the remaining challenges in order to make it an hand-on computational tool.

296 citations

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TL;DR: An Optimized PS (OPS) scheme is presented for accurate and consistent implementation of particle shifting for free-surface flows, consistently resulting in perfect elimination of shifting normal to an interface and resolves the unphysical discontinuity beneath the interface.

248 citations

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TL;DR: In this paper, the authors provide an up-to-date review on several latest advancements related to particle methods with applications in coastal and ocean engineering and highlight the future perspectives for further enhancement of applicability and reliability of particle methods for coastal/ocean engineering applications.
Abstract: The article aims at providing an up-to-date review on several latest advancements related to particle methods with applications in coastal and ocean engineering. The latest advancements corresponding to accuracy, stability, conservation properties, multiphase multi-physics multi-scale simulations, fluid-structure interactions, exclusive coastal/ocean engineering applications and computational efficiency are reviewed. The future perspectives for further enhancement of applicability and reliability of particle methods for coastal/ocean engineering applications are also highlighted.

245 citations