The Experts below are selected from a list of 765 Experts worldwide ranked by ideXlab platform
Hongyuan Jiang - One of the best experts on this subject based on the ideXlab platform.
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efficient particle and droplet manipulation utilizing the combined thermal Buoyancy Convection and temperature enhanced rotating induced charge electroosmotic flow
Analytica Chimica Acta, 2020Co-Authors: Kailiang Zhang, Tianyi Jiang, Xiaokang Deng, Hongyuan JiangAbstract:Abstract Efficient granular sample manipulation is crucial for various microfluidic-based applications such as material synthesis and drug delivery. Herein we present a novel method to efficiently manipulate microbeads and droplets using the combined thermal Buoyancy Convection and temperature-enhanced rotating induced-charge electroosmotic flow. Within the granular fluid, a pair of counter-rotating microvortices is formed above the floating electrode, leading to the formation of a flow stagnation region at the bottom center. Granular samples then can be effectively transported to this region by the Stokes drag, and the concentration performance can be flexibly manipulated by adjusting the energization strategies of the chip. The contributions of fluid Convection, dielectrophoresis, thermophoresis, and gravity force to particle migration are first studied and compared, proving that the Convection flow and gravity force are mainly responsible for particle migration and deposition respectively. Then the systematic enriching experiments of 4-μm silica particles demonstrate that the particle migration velocity can be highly improved by the combined thermal-electrical field. Finally, the effective concentration of nanocopper particles and the assembly of oil-in-water/water-in-oil-in-water droplets indicate that this approach is capable of manipulating diverse granular samples. Therefore, this strategy can be attractive for lots of microfluidic-based applications because of its high efficiency and simplicity.
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Flexible Particle Focusing and Switching in Continuous Flow via Controllable Thermal Buoyancy Convection.
Analytical Chemistry, 2020Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan JiangAbstract:We present a novel approach that utilizes thermal Buoyancy Convection to achieve flexible particle focusing and switching in continuous flow of a microfluidic system. In this platform, three strip ...
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Continuous microfluidic mixing and the highly controlled nanoparticle synthesis using direct current-induced thermal Buoyancy Convection
Microfluidics and Nanofluidics, 2019Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan JiangAbstract:We present a flexible and noninvasive approach for efficient continuous micromixing and microreaction based on direct current-induced thermal Buoyancy Convection in a single microfluidic unit. Theoretically, microfluids in this microsystem are unevenly heated by powering the asymmetrically arranged microheater. The thermal Buoyancy Convection is then formed to induce microvortices that cause effective fluidic interface disturbance, thereby promoting the diffusion and convective mass transfer. The temperature distribution and the Convection flow in the microchip are first characterized and studied, which can be flexibly adjusted by changing the DC voltage. Then the mixing performance of the presented method is validated by joint numerical and experimental analyses. Specifically, at U = 7 V, the mixing efficiencies are higher than 90% as the flow rate is lower than Qv= 600 nL/s. So high-quality chemical or biochemical reactions needing both suitable heating and efficient mixing can be achieved using this method. Finally, as one example, we use this method to synthesize nano-sized cuprous oxide (Cu2O) particles by effectively mixing the Benedict’s solution and glucose buffer. Remarkably, the particle size can be tuned by changing the voltage and the concentration of Benedict’s solution. Therefore, this micromixer can be attractive for diverse applications needing homogeneous sample mixtures.
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Efficient Micro/Nanoparticle Concentration using Direct Current-Induced Thermal Buoyancy Convection for Multiple Liquid Media.
Analytical Chemistry, 2019Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan JiangAbstract:Thermal-based microparticle focusing has recently received increasing attention due to its noninvasive nature and simple manipulation mechanism. However, its further application is limited by current complicated fluid heating systems and low particle focusing velocity. Using simple indium tin oxide-made microheaters, herein we propose a flexible and novel approach for efficient particle focusing based on direct current-induced thermal Buoyancy Convection. Importantly, for avoiding possible electrochemical reactions on the electrode, the microheaters are isolated from the granular fluids of interest by a thin glass slide. The concentration performance of the designed chip was first demonstrated by statically focusing 4-μm silica particles, yeast cells, silica particles in insulating buffer, and 100-nm copper microspheres. Also the trapping of a mixture of 5-μm and 2-μm polystyrene microbeads indicated that the chip can either simultaneously concentrate two kinds of particles or selectively focus the heavie...
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efficient micro nanoparticle concentration using direct current induced thermal Buoyancy Convection for multiple liquid media
Analytical Chemistry, 2019Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan JiangAbstract:Thermal-based microparticle focusing has recently received increasing attention due to its noninvasive nature and simple manipulation mechanism. However, its further application is limited by current complicated fluid heating systems and low particle focusing velocity. Using simple indium tin oxide-made microheaters, herein we propose a flexible and novel approach for efficient particle focusing based on direct current-induced thermal Buoyancy Convection. Importantly, for avoiding possible electrochemical reactions on the electrode, the microheaters are isolated from the granular fluids of interest by a thin glass slide. The concentration performance of the designed chip was first demonstrated by statically focusing 4-μm silica particles, yeast cells, silica particles in insulating buffer, and 100-nm copper microspheres. Also the trapping of a mixture of 5-μm and 2-μm polystyrene microbeads indicated that the chip can either simultaneously concentrate two kinds of particles or selectively focus the heavie...
Yuwen Zhang - One of the best experts on this subject based on the ideXlab platform.
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coupling diffusive effects on thermosolutal Buoyancy Convection in a horizontal cavity
Numerical Heat Transfer Part A-applications, 2015Co-Authors: Jin Wang, Mo Yang, Yuwen ZhangAbstract:Coupling–diffusive effects on thermosolutal Buoyancy Convection with Soret and Dufour effects in a horizontal cavity are investigated numerically. The problem is formulated using a coupling–diffusive model for thermosolutal Buoyancy Convection and is solved by the SIMPLE algorithm with the QUICK scheme in a nonuniform staggered grid system. The results show that thermal and solutal Buoyancy primarily dominate the structure of the velocity field and that the inflexion points of flow pattern transform as Rayleigh number or Buoyancy ratio increases. The parametric study shows that the heat and mass transfer of thermosolutal Convection are enhanced as Rayleigh number or Buoyancy ratio increases. Soret and Dufour effects have a linear influence on heat and mass transfer in a horizontal cavity so that the coupling–diffusive effects cannot be ignored, especially under high Rayleigh numbers.
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Coupling–Diffusive Effects on Thermosolutal Buoyancy Convection in a Horizontal Cavity
Numerical Heat Transfer Part A-applications, 2015Co-Authors: Jin Wang, Mo Yang, Yuwen ZhangAbstract:Coupling–diffusive effects on thermosolutal Buoyancy Convection with Soret and Dufour effects in a horizontal cavity are investigated numerically. The problem is formulated using a coupling–diffusive model for thermosolutal Buoyancy Convection and is solved by the SIMPLE algorithm with the QUICK scheme in a nonuniform staggered grid system. The results show that thermal and solutal Buoyancy primarily dominate the structure of the velocity field and that the inflexion points of flow pattern transform as Rayleigh number or Buoyancy ratio increases. The parametric study shows that the heat and mass transfer of thermosolutal Convection are enhanced as Rayleigh number or Buoyancy ratio increases. Soret and Dufour effects have a linear influence on heat and mass transfer in a horizontal cavity so that the coupling–diffusive effects cannot be ignored, especially under high Rayleigh numbers.
Zhiwu Chen - One of the best experts on this subject based on the ideXlab platform.
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Double-diffusive Buoyancy Convection in a square cuboid with horizontal temperature and concentration gradients
International Journal of Heat and Mass Transfer, 2013Co-Authors: Zhiwu Chen, Jie-min Zhan, Yok-sheung LiAbstract:Double-diffusive Buoyancy Convection in a three-dimensional (3D) square cuboid is studied in the present paper. Both the temperature and solute concentration gradients are applied horizontally. Direct numerical simulations are carried out for Rayleigh number 10
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double diffusive Buoyancy Convection in a square cuboid with horizontal temperature and concentration gradients
International Journal of Heat and Mass Transfer, 2013Co-Authors: Zhiwu Chen, Jie-min Zhan, Yok-sheung LiAbstract:Double-diffusive Buoyancy Convection in a three-dimensional (3D) square cuboid is studied in the present paper. Both the temperature and solute concentration gradients are applied horizontally. Direct numerical simulations are carried out for Rayleigh number 10 <= Ra <= 2 x 10(5), Buoyancy ratio -2 <= R-rho <= 0, and Lewis number 2 <= Le <= 1000. Different front-rear symmetric solutions are found, and the flow structures are essentially three-dimensional. As each of the parameters is varied, typical pitchfork bifurcation is encountered, given appropriate disturbances. The resultant asymmetric solution presents a diagonal flow configuration. Different solution branches are denoted in terms of Nusselt and Sherwood numbers and corresponding two-dimensional (2D) model results are also presented to depict the deviations. In some parameter ranges, the 2D model significantly over-predicts the heat and mass transfer rates. More importantly, it fails to predict any unsteadiness of the flow, even when the corresponding 3D solution is chaotic. The onset of Convection from the quiescent equilibrium state is also considered. (C) 2013 Elsevier Ltd. All rights reserved.
Shintaroh Kida - One of the best experts on this subject based on the ideXlab platform.
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Transient mass transfer rate of Cu2+ion caused by copper electrodeposition with alternating electrolytic current
Electrochimica Acta, 2010Co-Authors: S Kawai, KUNIAKI ISHIBASHI, M. Ogawa, Yasuhiro Fukunaka, T. Matsuoka, T. Homma, Y. Kondo, Shintaroh KidaAbstract:Copper electrolysis is carried out in a stagnant 0.05 M CuSO4aqueous electrolyte under alternating current (AC) condition. Transient mass transfer rate of Cu2+ion caused by copper electrodeposition with AC is studied theoretically and experimentally with the holographic interferometer. The effect of Buoyancy Convection developing along the vertical plane electrodes on the transient concentration boundary layer (CBL) structure accompanying with AC is focused on. Two different electrode configurations, the horizontal cathode over anode and the vertical electrode settings, are employed for this purpose. The CBL thickness tends to increase over long duration time in the former configuration, while it converges to a steady-state value in the latter. Both calculated and measured concentration profiles in the vertical electrode configuration exhibit the characteristic transient behaviors composed of the pulsating CBL (PCBL) in the vicinity of the cathode surface and the stationary CBL (SCBL) outside the PCBL. The appearance of the SCBL is ascribed to mass transfer by advection, and the overall CBL thickness depends on the hydrodynamic conditions such as the magnitude of Buoyancy Convection. © 2010 Elsevier Ltd. All rights reserved.
You-rong Li - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on the effect of surface evaporation on the thermocapillary-Buoyancy Convection in a shallow annular pool
International Journal of Heat and Mass Transfer, 2019Co-Authors: Jin-jing Li, You-rong Li, Lu Zhang, Li Zhang, Xiaojun QuanAbstract:Abstract In order to understand effect of surface evaporation on thermocapillary-Buoyancy Convection, a series of experiments on thermocapillary-Buoyancy Convection in a shallow annular pool with different surface evaporation rates have been conducted. The annular pool is subjected to a radial temperature gradient, and the inner and outer radii are respectively 20 mm and 40 mm. The 0.65 cSt silicone oil has been selected as the working fluid for its relatively strong volatility. Results show that the surface evaporation rate depends mainly on Marangoni number and the average temperature of the working fluid. At a weak evaporation, the critical Marangoni number increases with the increase of the surface evaporation rate and the liquid pool depth, i.e. the surface evaporation and Buoyancy effects can suppress the flow destabilization. When the three-dimensional flow appears, the temperature fluctuation from the hydrothermal waves and the free surface fluctuation of the liquid layer are regular and coincident. However, in the case of the rapid evaporation, the vapor recoil can directly trigger the flow instability. Furthermore, the temperature fluctuation is weakened significantly, and the surface fluctuation of the liquid layer become irregular due to the vapor recoil effect.
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Experimental study on Prandtl number dependence of thermocapillary-Buoyancy Convection in Czochralski configuration with different depths
International Journal of Thermal Sciences, 2018Co-Authors: You-rong Li, Lu Zhang, Li Zhang, Jia-jia YuAbstract:Abstract A series of experiments on thermocapillary-Buoyancy Convection in Czochralski configuration with different liquid depths have been conducted. Prandtl numbers of the working fluids vary from 10 to 29 and the depth of the liquid pool is between 1.5 mm and 8 mm. Results show that the critical Marangoni number increases with the increase of the liquid pool depth. Prandtl number has a little impact on the critical Marangoni number for the shallow liquid pool, but a significant influence for the deep liquid pool. The flow pattern transits from the concentric multi-rolls to the hydrothermal waves in the shallow liquid pool with the increase of Marangoni number. Furthermore, with the increase of Prandtl number and the liquid pool depth, the hydrothermal waves can be suppressed, and thus the concentric multi-rolls flow pattern is easier to appear. In deep liquid pools, the number of the spokes decreases with the increase of Marangoni number and the liquid pool depth, and the spokes move from the crystal edge to the crucible sidewall. In addition, the radical waves close to the crystal edge have been observed at deep liquid pools and large Marangoni numbers.
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effect of capillary ratio on thermal solutal capillary Buoyancy Convection in a shallow annular pool with radial temperature and concentration gradients
International Journal of Heat and Mass Transfer, 2017Co-Authors: You-rong Li, Chun-mei Wu, Jiechao Chen, Jia-jia YuAbstract:Abstract In order to understand the effect of capillary ratio on the thermal-solutal capillary-Buoyancy Convection in an annular pool subjected to simultaneous radial thermal and solutal gradients, a series of three-dimensional direct numerical simulations have been carried out. The working fluid was the toluene/n-hexane mixture fluid with the Prandtl number of 5.54 and the Schmidt number of 142.8. The capillary ratio Rσ varied from −0.8 to 0.2. Results show that the flow is axisymmetric and steady at small thermocapillary Reynolds number. Four types of such two-dimensional steady flow, i.e., counter-clockwise unicellular flow, clockwise unicellular flow, flows with two separate cells stratified horizontally and vertically, appear with the variations of capillary ratio and thermocapillary Reynolds number. With the further increase of thermocapillary Reynolds number, two-dimensional steady flow bifurcates firstly to three-dimensional steady flow at the first critical thermocapillary Reynolds number, then to three-dimensional oscillatory flow at the second critical thermocapillary Reynolds number. When the three-dimensional oscillatory flow appears, the temperature and concentration fluctuations on the free surface are indicated as either the coexistence of “hydro-thermal wave” and “hydro-solutal wave”, or the “vibrating straight spokes”. A reverse transition from periodic flow to steady flow is encountered.
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Three-dimensional numerical simulation of double-diffusive Rayleigh–Bénard Convection in a cylindrical enclosure of aspect ratio 2
International Journal of Heat and Mass Transfer, 2016Co-Authors: You-rong Li, Li Zhang, Huan Zhang, Chun-mei WuAbstract:Abstract This paper presented a series of three-dimensional numerical simulations on the double-diffusive Rayleigh–Benard Convection in a cylindrical enclosure filled with the isopropanol/water mixture with an initial mass fraction of 10%. The Prandtl number and the Lewis number of the isopropanol/water mixture were 13.2 and 140.2, respectively. The cylindrical enclosure was heated at the bottom wall and cooled at the top wall. Results show that the ratio of the solutal Buoyancy to thermal Buoyancy has an important effect on flow pattern formation and bifurcation sequences. For cooperating Buoyancy Convection, an unsteady flow appears foremost, and then four typical steady flow patterns happen orderly. For opposing Buoyancy Convection, only five types of oscillatory flow patterns are detected, which are characterized by azimuthal rotation. The critical Rayleigh number at the primary threshold is strongly influenced by concentration gradient, and decreases with the increase of the Buoyancy ratio. Different solution branches are denoted in terms of the Nusselt number, which depends primarily on the Rayleigh number and the flow pattern. Furthermore, the several flow pattern coexistence and hysteresis phenomenon of the flow pattern transition in double-diffusive Rayleigh–Benard Convection have also been confirmed.
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Linear-stability analysis of thermocapillary-Buoyancy Convection in annular two-layer system with a radial temperature gradient
International Communications in Heat and Mass Transfer, 2015Co-Authors: Xi-wu Gong, Dong-ming Mo, Chun-mei Wu, You-rong LiAbstract:Abstract In this paper, we present a set of linear-stability analysis results of the thermocapillary-Buoyancy Convection in an annular two-layer system of 5cSt silicone oil and HT-70 with a radial temperature gradient. The annular two-layer system is heated at the outer cylindrical wall and cooled at the inner wall. The effects of the depth ratio, the radius ratio and the aspect ratio of the annular pool on the critical conditions for the Convection transition are analyzed. The flow destabilizing mechanism is identified. Results indicate that the hydrothermal wave, or the combined hydrothermal wave and three-dimensional oscillatory flow, should be responsible for the flow destabilization when the stable thermocapillary-Buoyancy Convection transits to the three-dimensional oscillatory Convection. With the increase of the radius ratio of the annular pool, the critical Marangoni number, wave number and phase velocity all decrease. With the increase of the depth ratio η, the critical Marangoni number initially increases before a dramatic decrease. The maximum value of the critical Marangoni number locates in the range of η = 0.625–0.833.