Shaopeng Liu¹, Guowei Wang^2,3,*, Pengfei Liu¹, Dong Ye¹, Jian Song¹, Xing Liu¹, Yang Cheng^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.12, pp. 3045-3058, 2023, DOI:10.32604/fdmp.2023.029810

Abstract Foam drainage is the flow of liquid through the interstitial spaces between bubbles driven by capillarity and gravity and resisted by viscous damping. The so-called foam drainage gas recovery technology is a technique traditionally used to mitigate the serious bottom-hole liquid loading in the middle and late stages of gas well production. In this context, determining the optimal concentration of the bubble drainage agent is generally crucial for the proper application of this method. In this study, a combination of indoor experiments and theoretical analysis have been used to determine the pressure drop related to… More >

Ying Zhang^1,*, Weiming Niu², Leibing Yan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.1, pp. 885-902, 2024, DOI:10.32604/cmes.2023.029234

Abstract In this paper, we consider mobile edge computing (MEC) networks against proactive eavesdropping. To maximize the transmission rate, IRS assisted UAV communications are applied. We take the joint design of the trajectory of UAV, the transmitting beamforming of users, and the phase shift matrix of IRS. The original problem is strong non-convex and difficult to solve. We first propose two basic modes of the proactive eavesdropper, and obtain the closed-form solution for the boundary conditions of the two modes. Then we transform the original problem into an equivalent one and propose an alternating optimization (AO) More >

Fulai Cao^1,*, Yanpu Chao^1,*, Hao Yi^2,3, Shuai Lu¹, Chengshui Guo⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.11, pp. 2891-2905, 2023, DOI:10.32604/fdmp.2023.029243

Abstract The properties of droplets produced by existing on-demand injection systems are typically determined by the nozzle diameter, i.e., only droplets with size larger than this diameter can be obtained. To solve this problem, a system for electric field-driven droplet injection and deposition was developed, and the related performances were compared with those of a standard pneumatic system. The results show that the diameter of droplets generated accordingly can be significantly smaller than the nozzle diameter. In particular, the effects of frequency and duty ratio on the number of droplets were studied by assuming microcrystalline wax More > Graphic Abstract

Karema A. Hamad^*, Yasser A. Mahmood

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.11, pp. 2863-2875, 2023, DOI:10.32604/fdmp.2023.029049

Abstract The cooling of a (pebble bed) spent fuel in a high-temperature gas-cooled reactor (HTGR) is adversely affected by an increase in the temperature of the used gas (air). To investigate this problem, a configuration consisting of three copper spheres arranged in tandem subjected to a forced mist flow inside a cylindrical channel is considered. The heat transfer coefficients and related variations as a function of Reynolds number are investigated accordingly. The experimental results show that when compared to those with only airflow, the heat transfer coefficient of the spherical elements with mist flow (j = More >

Hongfei Ye^1,*, Chenguang Yin¹, Jian Wang¹, Yonggang Zheng¹, Hongwu Zhang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.1, pp. 1-1, 2023, DOI:10.32604/icces.2023.09741

Abstract The wetting behavior is ubiquitous in natural phenomenon as well as engineering application. As an intrinsic property of solid surface, the wettability with a controllable gradient has been an attractive issue with a wide application in various fields, including microfluidic devices, self-driven transport, biotechnologies, etc. Generally, it often requires elaborate design of microstructure or its response under the electrical, thermal, optical, pH stimuli, etc. However, the relevant complex underlying mechanism makes it difficult to construct quantitative relations between the wettability and the external field for the fine design. In this work, based on the bilayer… More >

Fujian Zhang¹, Xiang Gao¹, Zhongqiang Zhang^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.09169

Abstract Biological features such as the bumps on the back of desert beetles and the spikes of cacti enable the directional transport of water droplets, creating conditions for their survival in nature. Inspired by the interesting natural phenomenon, a novel design of nanopillared surface with a gradient density of structural pillar matrix covered by a monolayer graphene is proposed to realize ultrafast self-driving of water droplets. The droplet can move spontaneously at ultrahigh speed of 75.7 m/s (272.52 km/h) from sparsest to densest regions of pillars while a wettability gradient is created by the gradient distribution… More >

Yue Hu¹, Lu-Wen Zhang^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.1, pp. 1-1, 2023, DOI:10.32604/icces.2023.010595

Abstract Liquid accretion control plays a key role across a wide range of industrial applications, such as anti-icing, power generation, sewage treatment, water desalination, and energy harvesting. In condensation system, durable dropwise condensation of saturated vapor for heat transfer and energy saving in extensive industrial applications. While numerous superhydrophobic surfaces can promote steam condensation, maintaining discrete microdroplets on surfaces without the formation of a flooded filmwise condensation at high subcooling remains challenging. Here, we report the development of carbon nanotube arrayembedded hierarchical composite surfaces that enable ultra-durable dropwise condensation under a wide range of subcooling temperatures (∆T_sub… More >

Yunyun Song¹, Xu Zhang¹, Jialei Yang¹, Zhongqiang Zhang^1,*, Guanggui Cheng¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.2, pp. 1-1, 2023, DOI:10.32604/icces.2023.09916

Abstract Although floating oil with large particle sizes can easily be separated from water by membrane separation methods, tiny oil droplets with tremendously small volume force and density gradient at oil-water interfaces within water lead to barriers of oil-water separation. Consequently, tiny oil droplets remain in the water, resulting in energy waste, environmental pollution and biological health hazard. Traditional super-wetting membranes with extremely small pore sizes were easily blocked during the oil-water separation process. Inspired by the cactus and rice leaf, we developed a superhydrophobic-superoleophilic surface with conical micro-arrays to realize ultrafast adsorption of tiny oil… More >

Yuhang Wang^1,2, Gaojin Li^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.2, pp. 1-2, 2023, DOI:10.32604/icces.2023.09895

Abstract The chemically active droplets, which converts the chemical energy into a localized fluid flow at the interfaces by generating a concentration gradients of surfactant, can realize self-propulsion with complex trajectories and have been widely studied to mimic the swimming behavior of micro-organisms. In reality, the motion of chemically active droplets is influenced by a combination of diffusiophoresis and Marangoni effect under concentration gradients of surfactant. However, the interaction between these two effects has been only studied for a drop under the constraint of the axial-symmetric motion. To understand the hydrodynamics of the unconstraint motion, we… More >

AlemKarima^a,*, Sahel Djamel^b , Nemdili Ali^c, Ameur Houari^d

Frontiers in Heat and Mass Transfer, Vol.10, pp. 1-7, 2018, DOI:10.5098/hmt.10.27

Abstract In the present paper, the effects of a new baffle design on the efficiency of a tubular heat exchanger are numerically investigated. It concerns butterfly baffles inserted in a cylindrical tube heat exchanger. We focus on the influence of the shape of baffles, the space between baffles (pitch ratio, PR) and the baffle size (i.e. the blockage ratio, BR) on the heat transfer and flow characteristics. Three geometrical configurations with different PRs are realized (PR = 1, 2 and 4) and five others with different blockage ratios (BR = 0.1, 0.2, 0.3, 0.4 and 0.5). More >