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  • Open Access


    Improvements for calculating two-phase bubble and drop motion using an adaptive sharp interface method.

    Mark Sussman1, Mitsuhiro Ohta2

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.1, pp. 21-36, 2007, DOI:10.3970/fdmp.2007.003.021

    Abstract In this paper, we describe new techniques for numerically approximating two-phase flows. Specifically, we present new techniques for treating the viscosity and surface tension terms that appear in the Navier-Stokes equations for incompressible two-phase flow. Our resulting numerical method has the property that results computed using our two-phase algorithm approach the corresponding "one-phase'' algorithm in the limit of zero gas density/viscosity; i.e. the two-phase results approach the one-phase free-boundary results in the limit that the gas is assumed to become a uniform pressure void. By grid convergence checks and comparison with previous experimental data, we shall demonstrate the advantages of… More >

  • Open Access


    Surface Phase Separation and Flow in a Simple Model of Multicomponent Drops and Vesicles

    J.S. Lowengrub1, J-J. Xu2, A. Voigt3

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.1, pp. 1-20, 2007, DOI:10.3970/fdmp.2007.003.001

    Abstract We introduce and investigate numerically a thermodynamically consistent simple model of a drop or vesicle in which the interfacial surface contains multiple constitutive components (e.g. amphiphilic molecules). The model describes the nonlinear coupling among the flow, drop/vesicle morphology and the evolution of the surface phases. We consider a highly simplified version of the Helfrich model for fluid-like vesicle membranes in which we neglect the effects of bending forces and spontaneous curvature but keep the effects of inhomogeneous surface tension forces. Thus, this model may also describe liquid drops. To solve the highly nonlinear, coupled system a new numerical method is… More >

  • Open Access


    On the Dynamic Capillary Effects in the Wetting and evaporation process of Binary Droplets

    K. Sefiane1

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 267-276, 2005, DOI:10.3970/fdmp.2005.001.267

    Abstract In this paper the experimental results on the wetting behaviour of volatile binary sessile drops are reported. The evaporation rate is varied through the control of the ambient total pressure. The dynamic wetting contact angle of an evaporating Water-Ethanol drop is investigated at various sub-atmospheric pressures. The wetting properties (contact angle, shape and volume) are monitored in time using a drop shape analysis instrument. The results show that the evaporation of the binary droplet takes place in two stages: the first stage where the wetting behaviour is very similar to the pure ethanol case and a second stage where the… More >

  • Open Access


    Locomotion of a Viscous Drop, Induced by the Internal Secretion of Surfactant: Boundary Effects

    O.M. Lavrenteva1, D. Tsemakh, A. Nir

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 131-152, 2005, DOI:10.3970/fdmp.2005.001.131

    Abstract We have studied the motion of a drop, induced by the internal secretion of a surface-active substance, in the vicinity of solid walls or non-deformable liquid-liquid interface under micro-gravity conditions. The secreted substance renders a non-uniform distribution of surfactant along the outer surface that, in turn, results in interfacial stress variation that ultimately leads to a surface motion and to locomotion of the drop. Cases of plane and spherical boundaries have been considered as well as cases of linear and non-linear dependence of the interfacial tension on concentration of surfactant. The dependence of the drop migration velocity on the location… More >

  • Open Access


    Taguching the Atmospheric Plasma Spraying Process: Influence of Processing Factors on Droplet Impact Properties Obtained on Dense ZrO2 and H2Ar75% Plasma Gas

    Ridha Djebali1, Mohsen Toujani2, Bernard Pateyron3

    CMC-Computers, Materials & Continua, Vol.37, No.3, pp. 147-160, 2013, DOI:10.3970/cmc.2013.037.147

    Abstract In this paper a study of the atmospheric plasma spraying process was conducted. The Jets&Poudres code was used to solve the partial differential equations for the conservation of mass, momentum and energy involved in the problem together with the K-e turbulent model. The Taguchi technique was used to study the influence of processing factors on droplet impact properties obtained on dense zirconia (ZrO2) under H2Ar75% plasma gas that allow optimal functioning condition. The test of the operating parameters for the studied ranges showed that the "thermal power" factor plays a key role on the state of sprayed powder. It was… More >

  • Open Access


    On the Contact Characteristics between Droplet and Microchip/Binding Site for Self-Alignment

    Wen-Hwa Chen1,2, Tsung-Yu Huang1

    CMC-Computers, Materials & Continua, Vol.20, No.1, pp. 63-84, 2010, DOI:10.3970/cmc.2010.020.063

    Abstract The contact characteristics between a droplet and a microchip/binding site strongly affect the accuracy of self-alignment in the self-assembly of micro-electronic-mechanical systems. This study is mainly to implement the Surface Evolver Program, which is commonly adopted for studying surface shaped by surface tension and other energies, to investigate comprehensively the contact characteristics between the small droplet and the microchip/binding site. The details of changes in the contact line and the contact area when the microchip is subjected to translation, compression, yawing and rolling are drawn. The three-dimensional deformation of the droplet between the microchip and the binding site is also… More >

  • Open Access


    Hydroplaning Analysis for Tire Rolling over Water Film with Various Thicknesses Using the LS-DYNA Fluid-Structure Interactive Scheme

    Syh-Tsang Jenq1,2, Yuen-Sheng Chiu2

    CMC-Computers, Materials & Continua, Vol.11, No.1, pp. 33-58, 2009, DOI:10.3970/cmc.2009.011.033

    Abstract Current work studies the transient hydroplaning behavior of 200 kPa inflated pneumatic radial tires with various types of tread patterns. Tires were numerically loaded with a quarter car weight of 4 kN, and then accelerated from rest rolling over a water film with a thickness of 5, 10 and 15 mm on top of a flat pavement. Tire structure is composed of outer rubber tread and inner fiber reinforcing composite layers. The Mooney-Rivlin constitutive law and the classical laminated theory (CLT) were, respectively, used to describe the mechanical behavior of rubber material and composite reinforcing layers. The tire hydroplaning phenomenon… More >

  • Open Access


    Assessment of VOF Strategies for the Analysis of Marangoni Migration, Collisional Coagulation of Droplets and Thermal Wake Effects in Metal Alloys Under Microgravity Conditions

    Marcello Lappa 1

    CMC-Computers, Materials & Continua, Vol.2, No.1, pp. 51-64, 2005, DOI:10.3970/cmc.2005.002.051

    Abstract A possible approach for the investigation of a number of aspects related to the processing of immiscible alloys, made possible by recent progress in both fields of moving boundary (VOF) methods and speed of computers, is discussed. It can capture in a single numerical treatment and without limiting assumptions both macroscopic information (i.e. the macrophysical problem, heretofore treated in terms of population dynamics) and microscopic details (i.e. the microphysical problem, heretofore treated within the framework of boundary integral methods and/or under the assumption of nondeformable drops). The role played by coalescence in changing the Marangoni migration velocity is discussed together… More >

  • Open Access


    The Simulation of Diaphragm Deflection Actuated by Shear Mode Piezoelectric Actuator in Microdroplet Ejector

    C. H. Cheng1, S. C. Chen2

    CMC-Computers, Materials & Continua, Vol.1, No.3, pp. 205-212, 2004, DOI:10.3970/cmc.2004.001.205

    Abstract A shear mode piezoelectric actuator is applied to deflect the diaphragm of pressure chamber in the droplet ejector or inkjet printhead. The deflection of the bulge-diaphragm and resulting swept volume is analyzed by analytical and numerical method. With free-body treatment of the model, the analytical exact solutions for the two free bodies of bulge-diaphragm and piezoelectric beam were obtained. Also, the numerical solution by ANSYS is obtained to verify the analytical result. Besides, the whole-model solution coupling the bulge-diaphragm and piezoelectric beam together was obtained by ANSYS to compare with the result of free-body analysis. In order to estimate the… More >

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