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Buoyancy Convection

The Experts below are selected from a list of 765 Experts worldwide ranked by ideXlab platform

Hongyuan Jiang – 1st expert on this subject based on the ideXlab platform

  • efficient particle and droplet manipulation utilizing the combined thermal Buoyancy Convection and temperature enhanced rotating induced charge electroosmotic flow
    Analytica Chimica Acta, 2020
    Co-Authors: Kailiang Zhang, Tianyi Jiang, Xiaokang Deng, Hongyuan Jiang

    Abstract:

    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.

  • Flexible Particle Focusing and Switching in Continuous Flow via Controllable Thermal Buoyancy Convection.
    Analytical Chemistry, 2020
    Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan Jiang

    Abstract:

    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 …

  • Continuous microfluidic mixing and the highly controlled nanoparticle synthesis using direct current-induced thermal Buoyancy Convection
    Microfluidics and Nanofluidics, 2019
    Co-Authors: Kailiang Zhang, Tianyi Jiang, Hongyuan Jiang

    Abstract:

    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.

Yuwen Zhang – 2nd expert on this subject based on the ideXlab platform

  • coupling diffusive effects on thermosolutal Buoyancy Convection in a horizontal cavity
    Numerical Heat Transfer Part A-applications, 2015
    Co-Authors: Jin Wang, Mo Yang, Yuwen Zhang

    Abstract:

    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.

  • Coupling–Diffusive Effects on Thermosolutal Buoyancy Convection in a Horizontal Cavity
    Numerical Heat Transfer Part A-applications, 2015
    Co-Authors: Jin Wang, Mo Yang, Yuwen Zhang

    Abstract:

    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 – 3rd expert on this subject based on the ideXlab platform

  • Double-diffusive Buoyancy Convection in a square cuboid with horizontal temperature and concentration gradients
    International Journal of Heat and Mass Transfer, 2013
    Co-Authors: Zhiwu Chen, Jie-min Zhan, Yok-sheung Li

    Abstract:

    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

  • double diffusive Buoyancy Convection in a square cuboid with horizontal temperature and concentration gradients
    International Journal of Heat and Mass Transfer, 2013
    Co-Authors: Zhiwu Chen, Jie-min Zhan, Yok-sheung Li

    Abstract:

    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.