Jiajun Cui¹, Fabian Reuter², Zhigang Zuo^1,*, Shuhong Liu^1,*, Claus-Dieter Ohl^2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.4, pp. 1-1, 2024, DOI:10.32604/icces.2024.012155

Abstract When cavitation bubbles collapse near a boundary, they can cause severe cavitation erosion to the boundary, which is a dangerous threat to the rapidly rotating turbines. Prior research has established that for single bubbles a possible mechanism is energy focusing of shockwaves during the non-spherical collapse of cavitation bubbles [1]. This however needs a particularly symmetric environment. A possible approach to reduce the shockwave focusing and thus the erosion would be through suitable modification of the boundary. In a first approach to modify this phenomenon, we introduce the symmetry breaking structure on the boundary in the shape of a slender bar to explore the effect More >

Jie Wang^1,*, Jingyu Gu¹, Shuai Li¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.2, pp. 1-1, 2024, DOI:10.32604/icces.2024.012184

Abstract The interaction between the particle and the bubble under the ultrasonic wave excitation plays a pivotal role in various applications such as targeted therapy, ultrasonic cleaning, ultrasonography, and microbubble motors. When the particle is in close proximity or even attached to the bubble, a strong fluid-structure interaction occurs, significantly influencing the particle propulsion. The attachment of the bubble to the particle results in distinct bubble pulsation patterns and particle acceleration mechanisms from the non-contact state. Thus, we propose a fluid-structure interaction model based on the boundary integral method (BIM) to comprehensively consider the distance between More >

Wentao Wu¹, Qingyun Zeng^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.2, pp. 1-2, 2024, DOI:10.32604/icces.2024.012089

Abstract The collapses of bubbles near rigid walls are seen widely in engineering and medical applications, examples are surface cleaning, sonoporation, under water explosion, and cavitation erosions, to name a few. Recent experimental studies demonstrated that only bubbles with extremely small stand-off distance γ (γ = d/Rmax, γ is stand-off distance, d is the initial distance of the bubble center to the boundary, and Rmax is the maximum radius the bubble would attain) generate severe erosions during the first oscillating circle. This erosion phenomenon, attributed to a self-focusing mechanism, lacks a comprehensive explanation. Here we provided… More >

Zhesheng Zhao¹, Shuai Li¹, Rui Han^2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.2, pp. 1-1, 2024, DOI:10.32604/icces.2024.012080

Abstract This study investigates the interactions between droplets and bubbles within water-in-oil (O/W) and oil-in-water (W/O) systems, a fundamental problem of bubble dynamics in binary immiscible fluid systems. Considering the density ratio between the two fluids and the bubble-to-droplet size ratio, we have refined the classical spherical bubble pulsation equation, Rayleigh collapse time, and the natural frequency. In our experimental study, we found that the Rayleigh-Taylor (RT) instability hardly develops on the surface of the droplet when the densities of the two liquids are comparable. This phenomenon is explained using the classic theory of spherical RT More >

Leilei Wang¹, Li Chen², Haihang Cui², Xu Zheng^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.30, No.2, pp. 1-2, 2024, DOI:10.32604/icces.2024.011434

Abstract The emerging technique of artificial micro/nano-motors [1] provides a vivid example of the idea using tiny machines to finish jobs in microscopic world. Among many micro/nano-motors, microbubble driven micromotor is a unique type that can reach the highest propulsion speed [2, 3], owing to the high surface energy of the bubble and the focused hydrodynamic jet during bubble collapse that can significantly enhance micromotor’s propulsion. Recent progress has demonstrated that the microbubble itself can implement new functions for the micromotor based on bubble dynamics and induced hydrodynamic flow, rather than merely providing energy. For instance,… More >

Yang Cao^1,*, Jianshu Liu², Xuhui Meng¹

Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 675-685, 2024, DOI:10.32604/fhmt.2024.051208 - 20 May 2024

Abstract Boiling heat transfer, as an efficient heat transfer approach, that can absorb a large amount of latent heat during the vaporization, is especially suitable for heat transfer occasions with high heat flux demands. Experimental studies show that the surface tension coefficient of pure water can be reduced sharply (up to 25%) when it is magnetized by a magnetic field applied externally. In this paper, magnetized water (MW) was used as the work fluid to conduct boiling heat transfer experiments, to explore the influence of magnetization on the boiling characteristics of pure water. The electromagnetic device… More >

Ming He, Yunlong Liu^*, Shaofei Ren, Wentao Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.3, pp. 923-942, 2021, DOI:10.32604/cmes.2021.015259 - 24 May 2021

Abstract The fluid-structure interaction of the oscillating bubble and floating body with circular hole is essentially the nonlinear coupling problem among the incomplete movable boundary, free surface and bubble. This problem is particularly complicated in bubble dynamics. Combined with the volume of fluid method, the Eulerian finite element method is employed to deal with the fluid movement. Based on the improved penalty immersed boundary method, the transient axisymmetric numerical model is established in this paper, considering the fluid-structure interaction effect. The results of simulation are consistent with those of the electric discharge bubble experiment and explosion… More >

Xu Liu¹, Xiaoyang Chen^{1, *}, Rongyu Kang¹, Xuejin Shen¹, Ben Ni²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.1, pp. 129-152, 2020, DOI:10.32604/cmes.2020.07836 - 01 April 2020

Abstract In this paper, the oscillatory oil squeeze film is taken as a research object, and a coupled cavitation model based on the theory of bubble dynamics and hydrodynamic lubrication is used and a specific method of numerical calculation is given. Then the parallel-plate squeeze film test apparatus is used to validate the coupled cavitation model. The pictures of the cavitation were captured by a high-speed camera and then processed to obtain the variation of the cavitation area in experiments. Compared with the experimental results, the model can successfully predict the process of generation and development… More >

Zhaoli Tian^1,2, Yunlong Liu^1,2,*, Shiping Wang¹, A Man Zhang¹, Youwei Kang³

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.2, pp. 397-423, 2019, DOI:10.31614/cmes.2019.04419

Abstract The low frequency load of an underwater explosion bubble and the generated waves can cause significant rigid motion of a ship that threaten its stability. In order to study the fluid-structure interaction qualitatively, a two-dimensional underwater explosion bubble dynamics model, based on the potential flow theory, is established with a double-vortex model for the doubly connected bubble dynamics simulation, and the bubble shows similar dynamics to that in 3-dimensional domain. A fully nonlinear fluid-structure interaction model is established considering the rigid motion of the floating body using the mode-decomposition method. Convergence test of the model… More >

Tomio Okawa^*,†

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-8, 2012, DOI:10.5098/hmt.v3.1.3001

Abstract The present article summarizes the studies on the thermalhydraulic condition under which the onset of nucleate boiling (ONB) is triggered in subcooled flow boiling. Available correlations and experimental data show that the ONB is tended to be delayed in mini and microchannels. It is known that the ONB condition is significantly dependent on the surface condition even in conventional-sized channels. Accumulation of ONB data accompanied by the information on the surface condition is therefore considered of importance to elucidate the mechanisms of boiling incipience in microchannels. Discussion is also made for the bubble dynamics observed More >