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  • Open Access

    ARTICLE

    Contribution to knowledge of foliar anatomy on Mnesithea selloana (Hack.) de Koning & Sosef (Andropogoneae-Panicoideae-Poaceae)

    Moya ME1,2, AA Galussi1,2, MJ Gómez1,2, FG Marchese1,2

    Phyton-International Journal of Experimental Botany, Vol.84, No.1, pp. 176-183, 2015, DOI:10.32604/phyton.2015.84.176

    Abstract The aim of the present work was to analyze the foliar anatomy in lamina transverse section an in epidermis superficial view of Mnesithea selloana. Epidermic preparations and transections were carried out of the medium leaf part of sterile innovations that were conditioned and observed with optic microscope (OM) and scanning electron microscope (SEM).The histofoliar characteristics observed were: epidermic, intercostal, subsidiary, suberose, silicea and bulliform cells; and also guard cells, hairs, waxes, mesophylls, Kranz sheath, vascular bundles, sclerenchyma, colourless parenchyma and leaf margin. Epidermic observations showed that M. selloana presents a panicoid type epidermis presenting silicic cells as More >

  • Open Access

    ARTICLE

    Numerical Simulation of Droplet Breakup, Splitting and Sorting in a Microfluidic Device

    Chekifi. T1,2, Dennai. B1, Khelfaoui. R1

    FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.3, pp. 205-220, 2015, DOI:10.3970/fdmp.2015.011.205

    Abstract Droplet generation, splitting and sorting are investigated numerically in the framework of a VOF technique for interface tracking and a finite-volume numerical method using the commercial code FLUENT. Droplets of water-in-oil are produced by a flow focusing technique relying on the use of a microchannell equipped with an obstacle to split the droplets. The influence of several parameters potentially affecting this process is investigated parametrically towards the end of identifying "optimal" conditions for droplet breakup. Such parameters include surface tension, the capillary number and the main channel width. We show that the capillary number plays More >

  • Open Access

    ARTICLE

    COMPUTATIONAL STUDIES OF SWIRL RATIO AND INJECTION TIMING ON ATOMIZATION IN A DIRECT INJECTION DIESEL ENGINE

    Renganathan Manimarana, Rajagopal Thundil Karuppa Rajb,*

    Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.2

    Abstract Diesel engine combustion modeling presents a challenging task with the formation and breakup of spray into droplets. In this work, 3D-CFD computations are performed to understand the behaviour of spray droplet diameter and temperature during the combustion by varying the swirl ratio and injection timing. After the validation and grid and time independency tests, it is found that increase in swirl ratio from 1.4 to 4.1 results in peak pressure rise of 8 bar and an advancement of injection timing from 6 deg bTDC to 20 deg bTDC results in increase of peak pressure by More >

  • Open Access

    ARTICLE

    Simulations of Blood Drop Spreading and Impact for Bloodstain Pattern Analysis

    Chu Wang, Lucy T. Zhang1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.1, pp. 41-67, 2014, DOI:10.3970/cmes.2014.098.041

    Abstract Bloodstain pattern analysis (BPA) in forensic science is an important tool to solve crime scenes. The complex dynamic behavior of blood drops poses great challenges for accurate fluid dynamic simulations. In this paper, we specifically focus on simulations of blood drop spreading and impact, which may involve contact line hysteresis and spattering of drops as they interact with solid surfaces. Here, we set up a numerical framework that combines (1) the connectivity-free front tracking (CFFT) method for modeling multiphase (air and liquid) flows and (2) a dynamic contact line model for modeling fluid-solid contact line.… More >

  • Open Access

    ARTICLE

    Simulation of Thermal Fluid-structure Interaction Phenomena in a Liquid Sodium Porous System

    Yan Shen1, Hong Zhang1,2,3, Hui Xu1, Tong Bai1, Ping Yu1

    FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 63-81, 2014, DOI:10.3970/fdmp.2014.010.063

    Abstract Single-unit and multi-unit models of porous media (metal felts) have been used to investigate thermal fluid-structure interaction phenomena in a liquid sodium system. Micro-scale aspects have been studied via numerical simulations. The permeability of metal felts has been measured experimentally to verify the reliability of the models used. This integrated approach has allowed a proper evaluation of the interdependencies among phenomena on different scales (including relevant information on skeleton deformation and pressure drop as a function of different parameters). Pressure drop generally increases with velocity and heat flux for both laminar and turbulent flows. The More >

  • Open Access

    ARTICLE

    Synthesis and Characterization of New Carbohydrate-based Polyureas

    Belén Begines, Francisca Zamora, M. Violante de Paz, Isaac Roffé, Manuel Mancera, Juan A. Galbis*

    Journal of Renewable Materials, Vol.1, No.3, pp. 212-221, 2013, DOI:10.7569/JRM.2013.634119

    Abstract A batch of linear [m,n]-type sugar-based polyureas was synthesized by polyaddition reaction in solution from hexamethylene diisocyanate or 4,4’-methylene-bis(phenyl isocyanate) with the acyclic 2,3,4-tri-O-methyl-1,5- diamino-alditols having L-arabino, or xylo confi guration or the bicyclic 1,6-diamino-1,6-dideoxy-2,4:3,5-diO-methylene-D-glucitol. The polymers were obtained in good yields and fair molecular weights. All these polyureas were semicrystalline materials showing well-defi ned melting transition within the 86−171°C range, with Tg s being dependent on the aliphatic or aromatic nature of the diisocyanate used, and on the cyclic or acyclic chemical structure of the sugar moiety. They were found to be stable up to around More >

  • Open Access

    ARTICLE

    Thermocapillary Motion of a Spherical Drop in a Spherical Cavity

    Tai C. Lee1, Huan J. Keh2

    CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.5, pp. 317-333, 2013, DOI:10.3970/cmes.2013.093.317

    Abstract A theoretical study of the thermocapillary migration of a fluid sphere located at an arbitrary position inside a spherical cavity is presented in the quasisteady limit of small Reynolds and Marangoni numbers. The applied temperature gradient is perpendicular to the line through the drop and cavity centers. The general solutions to the energy and momentum equations governing the system are constructed from the superposition of their fundamental solutions in the spherical coordinates originating from the two centers, and the boundary conditions are satisfied by a multipole collocation method. Results for the thermocapillary migration velocity of… More >

  • Open Access

    ARTICLE

    Low and High Velocity Impact Studies on Fabric Reinforced Concrete Panels

    Smitha Gopinath1, C.K. Madheswaran1, A. Rama Ch,ra Murthy1, Nagesh. R. Iyer2, Barkavi.T3

    CMES-Computer Modeling in Engineering & Sciences, Vol.92, No.2, pp. 151-172, 2013, DOI:10.3970/cmes.2013.092.151

    Abstract This paper presents the details of experimental and numerical investigations performed on fabric reinforced concrete (FABcrete) panels under impact loading. Experimental investigations have been carried out using drop weight impact on a square FABcrete panel to study the damage, failure mode and acceleration. The drop weight of 20 kg is used for the study and drop heights have been varied as 100mm, 200mm and 300mm. Numerical simulation of the drop weight impact tests on FABcrete panels have been carried out and observed that there is a good correlation between experimental and numerical predictions. It is More >

  • Open Access

    ARTICLE

    Computational Studies on the Transient Electrohydrodynamics of a Liquid Drop

    Md. Abdul Halim1, Asghar Esmaeeli2

    FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.4, pp. 435-460, 2013, DOI:10.3970/fdmp.2013.009.435

    Abstract This study aims to gain a detailed understanding of the transient behavior of solitary liquid drops in electric fields at finite Reynolds number. A front tracking/finite difference method, in conjunction with Taylor-Melcher leaky dielectric model, is used to solve the governing electrohydrodynamic equations. The evolution of the flow field and drop deformation is studied for a few representative fluid systems, corresponding to the different regions of the deformation-circulation map. It is shown that for the range of the physical parameters used here, the deformationtime history is governed by one time scale while the fluid flow More >

  • Open Access

    ARTICLE

    Evaluation of some of the existing models for droplet and spray/wall interactions

    Davood Kalantari1

    FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 169-182, 2013, DOI:10.3970/fdmp.2013.009.169

    Abstract In this study, a critical summary of existing spray/wall interaction models is given in synergy with a review of available experimental data. In particular, special attention is devoted to the limitations, difficulties and complexities of the most used approaches in the literatures. An attempt is also made to indicate the bottlenecks and criticalities which typically arise when investigators try to extend results obtained for isolated droplets to the more complex dynamics produced by spray impacts. More >

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