COMPARISON ON BUBBLE DEFORMATION AND INFLUENCE ON WALL SHEAR STRESS IN SIMPLE SHEAR FLOW BETWEEN TWO- AND THREE-DIMENSIONAL COMPUTATIONS

IF 0.7 Q4 THERMODYNAMICS

Interfacial Phenomena and Heat Transfer Pub Date : 2019-01-01 DOI:10.1615/interfacphenomheattransfer.2019030134

Rui Niu, Ming Pang

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引用次数: 0

Abstract

Bubbly suspensions widely exist in many industrial fields, and thus it is very important to deeply investigate the physical properties of bubbly suspensions for the design and improvement of industrial products. In the present investigations on bubbly suspensions, twoand three-dimensional numerical simulations were performed, in which the obtained results showed some differences. To obtain an accurate and reasonable understanding of physical phenomena, it is necessary to clarify the similarities and differences of the computational results between twoand three-dimensional computations. Therefore, twoand three-dimensional computations are simultaneously carried out in order to study the behavior of a single bubble suspended in a Newtonian fluid under simple shear using the volume of fluid method. The trends of bubble deformation and influence on wall shear stress are analyzed in detail. The present study shows that the difference between the twoand three-dimensional computational results is related to the capillary number (Ca). When Ca ≤ 0.6, the computational results, including the bubble deformation and influence on the wall stress, are similar in the two kinds of computations; however, when Ca > 0.6, the results of the twoand three-dimensional computations show great differences. In the two-dimensional simulation, when the capillary number is relatively large, the bubble stretches and rocks, leading to unstable deformation. Correspondingly, the wall shear stress fluctuates with the bubble deformation. In the three-dimensional simulation, tip streaming occurs in the bubble. However, the wall shear stress remains stable after tip streaming appears.

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二维与三维简单剪切流中气泡变形及对壁面剪应力影响的比较

气泡悬浮液广泛存在于许多工业领域，因此深入研究气泡悬浮液的物理性质对工业产品的设计和改进具有十分重要的意义。在气泡悬浮液的研究中，分别进行了二维和三维数值模拟，所得结果存在一定的差异。为了准确合理地理解物理现象，有必要澄清二维和三维计算结果的异同。因此，采用流体体积法同时进行二维和三维计算，以研究单气泡悬浮在牛顿流体中在简单剪切作用下的行为。详细分析了气泡变形趋势及其对管壁剪应力的影响。研究表明，二维计算结果与三维计算结果的差异与毛细管数(Ca)有关。当Ca≤0.6时，两种计算的气泡变形及对壁面应力的影响计算结果相似;但当Ca > 0.6时，二维和三维计算结果差异较大。在二维模拟中，当毛细数较大时，气泡拉伸和岩石，导致不稳定变形。相应的，壁面剪应力随气泡变形而波动。在三维模拟中，气泡中出现了叶尖流动。而叶尖流出现后，壁面剪应力保持稳定。

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来源期刊

Interfacial Phenomena and Heat Transfer THERMODYNAMICS-

CiteScore

1.70

自引率

40.00%

发文量

期刊介绍： Interfacial Phenomena and Heat Transfer aims to serve as a forum to advance understanding of fundamental and applied areas on interfacial phenomena, fluid flow, and heat transfer through interdisciplinary research. The special feature of the Journal is to highlight multi-scale phenomena involved in physical and/or chemical behaviors in the context of both classical and new unsolved problems of thermal physics, fluid mechanics, and interfacial phenomena. This goal is fulfilled by publishing novel research on experimental, theoretical and computational methods, assigning priority to comprehensive works covering at least two of the above three approaches. The scope of the Journal covers interdisciplinary areas of physics of fluids, heat and mass transfer, physical chemistry and engineering in macro-, meso-, micro-, and nano-scale. As such review papers, full-length articles and short communications are sought on the following areas: intense heat and mass transfer systems; flows in channels and complex fluid systems; physics of contact line, wetting and thermocapillary flows; instabilities and flow patterns; two-phase systems behavior including films, drops, rivulets, spray, jets, and bubbles; phase change phenomena such as boiling, evaporation, condensation and solidification; multi-scaled textured, soft or heterogeneous surfaces; and gravity dependent phenomena, e.g. processes in micro- and hyper-gravity. The Journal may also consider significant contributions related to the development of innovative experimental techniques, and instrumentation demonstrating advancement of science in the focus areas of this journal.