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  • Open Access


    Computational Investigation of Droplets Behaviour inside Passive Microfluidic Oscillator

    Tawfiq Chekifi1, *, Brahim Dennai2, Rachid Khelfaoui2

    FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.3, pp. 173-187, 2017, DOI:10.3970/fdmp.2017.013.173

    Abstract Recently, modeling immiscible fluids such as oil and water have been a classical research topic. Droplet-based microfluidics presents a unique platform for mixing, reaction, separation, dispersion of drops and many other functions. In this paper, we suggest a numerical CFD study of microfluidic oscillator with two different lengths of feedback loop. In order to produce simultaneous droplets of gasoil on water, a typical geometry that includes double T-junction is connected to the fluidic oscillator. Droplets production is computed by volume-of-fluid method (VOF). Flow oscillations of droplets were triggered by the Coanda effect of jet flow. The aim of work is… More >

  • Open Access


    Lattice Boltzmann Simulation of Dynamic Behavior of Liquid Droplets on Solid Surfaces

    Masato Yoshino, Yoshito Tanaka, Keisuke Yano

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 131-132, 2011, DOI:10.3970/icces.2011.018.131

    Abstract Dynamics of droplet impact on solid surfaces is of great importance in many engineering applications such as ink-jet printing and rapid spray cooling of hot surfaces. In this study, the lattice kinetic scheme based on the lattice Boltzmann method for immiscible two-phase fluids [Inamuro (2006)] is applied to such micro-fluid problems. The present method enables us to perform stable calculations of two-phase flows with large density ratios of up to 1000. The boundary condition based on the wetting potential that is calculated according to a prescribed static contact angle is used on solid surfaces [Briant, Papatzacos, and Yeomans (2002)]. First,… More >

  • Open Access


    Numerical Simulation on the Influence of the Properties of Continuous Phase on Fluid Flow and Temperature Response in a Laser-Heated Suspended Droplet

    Long Jiao1,2, Zhibin Wang1,2, Rong Chen1,2,*, Xun Zhu1,2, Qiang Liao1,2, Dingding Ye1,2, Biao Zhang1,2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.3, pp. 144-146, 2019, DOI:10.32604/icces.2019.04734

    Abstract With the advances in micro total analysis systems (µTAS), the droplet-based microfluidics, which manipulates mini discrete droplets in an immiscible continuous phase to accomplish various detections, has been applied to many fields including medicine, pharmacy, fine-chemistry and biotechnology as it offers distinct advantages, such as small diffusion length, high-throughput, precise control and integratability [1]. As compared to the continuous-flow microfluidics, the samples in the droplet-based microfluidics are isolated by a defined droplet/continuous phase interface, avoiding the cross contamination and resulting in a controllable reaction environment. In the droplet-based microfluidics, the control of the droplet temperature with prominent temporal spatial resolution… More >

  • Open Access


    Three-dimensional simulations on the formation of droplets in a T-type microchannel

    Jr-Ming Miao1,2, Fuh-Lin Lih3, Yi-Chun Liou4, Hsiu-Kai Chen1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.1, pp. 33-34, 2009, DOI:10.3970/icces.2009.012.033

    Abstract To date, miniaturization of fluid handling and fluid analysis devices in the medicine engineering has been emerging in the interdisciplinary research field of micro-fluidics, as a result of miniaturization of the detective device to allow parallelization as well as to reduce analysis time and sample volume. Micro-total-analysis-system (μ -TAS) researches aimed at developing miniaturized and integrated ``lab-on-a-chip'' devices for biochemical analysis applications. Droplet-based micro-mixer is the one of the key components in the developing of μ-TAS. Numerical approach on the dynamic formation of water droplets in a T-type microchannel with a 200μm × 50μm rectangular cross section and 1000μm long… More >

  • Open Access


    Effects of throttling on the spray injection performance in a small LRE-injector

    Hun Jung1, Jin Seok Kim1, Jeong Soo Kim2, Jeong Park3

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 125-126, 2009, DOI:10.3970/icces.2009.011.125

    Abstract An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE) because it affects the evaporation rate of liquid fuel through spatial distribution and atomization of spray droplets. This paper is focused on the injection performance of a small LRE-Injector by employing the spray characteristic parameters made up of the velocity components, mean diameter, turbulence intensity, span (width of drop size distribution), number density, and volume flux of spray droplets. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along… More >

  • Open Access


    Kinetics of the ordered phase growth across the phase separation of a multi-component liquid crystalline mixture

    Sergei Bronnikov1, Sergei Kostromin, Vyacheslav Zuev

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.4, pp. 207-214, 2009, DOI:10.3970/icces.2009.009.207

    Abstract Kinetics of the ordered phase growth in a melted multi-component liquid crystalline mixture subjected to a deep cooling was studied using polarizing optical microscopy. The droplets of the ordered phase revealed in the optical images across the phase transition were segmented and treated statistically. In the resulting histograms, two overlapping statistical ensembles related to two main components of the mixture were recognized. These ensembles were successfully described using principles of irreversible thermodynamics and the mean droplet diameters within both ensembles were determined. Analysis of the mean droplet diameter as a function of time allowed recognition of two regimes involved in… More >

  • Open Access


    Analysis and Test on Influence Factors of Dew Drop Condensation in Dew Point Hygrometer

    Shijun Zhao1,2, Xiaoying Chen1,3,*, Xiaolei Wang1, Wenming Ji1, Zhonghua Dai4

    Journal of Quantum Computing, Vol.1, No.1, pp. 29-39, 2019, DOI:10.32604/jqc.2019.06112

    Abstract The condensation process of dew droplets is influenced by many factors. A dew point condensation image observation system was built to improve the response speed of dew point detector under different measuring conditions. The basic mechanism of dew drop condensation growth was studied and the influence of various factors on the dew drop growth rate were analyzed. And the accuracy of the influence results was verified based on the improved Hough transform circle detection. The results show that the growth rate of dew droplets is affected by ambient temperature, dew point temperature, mirror temperature and air velocity. The observed variation… More >

  • Open Access


    Numerical Modelling of Turbulence Effects on Droplet Collision Dynamics using the Level Set Method

    Ashraf Balabel1,

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 283-301, 2012, DOI:10.3970/cmes.2012.089.283

    Abstract This paper presents a novel numerical method for solving the twophase flow problems with moving interfaces in either laminar or turbulent flow regimes. The developed numerical method is based on the solution of the Reynolds- Averaged Navier Stokes equations in both phases separately with appropriate boundary conditions located at the interface separating the two fluids. The solution algorithm is performed on a regular and structured two-dimensional computational grid using the control volume approach. The complex shapes as well as the geometrical quantities of the interface are determined via the level set method. The numerical method is firstly validated against the… More >

  • Open Access


    Modeling the Wetting Effects in Droplet Impingement using Particle Method

    Heng Xie1, Seiichi Koshizuka2, Yoshiaki Oka2

    CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.1, pp. 1-16, 2007, DOI:10.3970/cmes.2007.018.001

    Abstract A model of a single liquid drop colliding on solid surface is developed based with Moving Particle Semi-implicit (MPS) method. The mathematical model involves gravity, viscosity and surface tension. The wettability between the impact liquid and the solid surface is modeled by the contact angle model and the non-slip boundary condition. The particles of the drop are divided into four types in which the model varies to simulate the liquid particles in different area. The model is validated by the comparison of the theoretical results. The complete dynamic process including the spreading, the recoiling, re-bouncing and splashing is simulated and… More >

  • Open Access


    Numerical Analysis on Unsteady Internal Flow in an Evaporating Droplet

    Zhentao Wang1,*, Kai Dong, Shuiqing Zhan

    FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.4, pp. 221-234, 2017, DOI:10.3970/fdmp.2017.013.221

    Abstract We have investigated the unsteady internal flow occurring in an evaporating droplet interacting with a high-temperature atmospheric environment. The Navier-Stokes equations for both the liquid and the gas phases have been solved numerically in the framework of a Volume of Fluid (VOF) method relying on the so-called Continuum Surface Force (CSF) model. A specific kernel able to account for evaporation and related phase change has been incorporated directly in the VOF approach. The temperature distributions within the droplet has been found to be relatively uniform by virtue of the Marangoni flow. The transient evolution of the flow pattern and related… More >

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