Search for: surface-wettability
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    Molecular dynamics simulation of nano channel as nanopumps

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011, Edmonton, AB ; Volume 2 , 2011 , Pages 223-227 ; 9780791844649 (ISBN) Darbandi, M ; Abbasi, H. R ; Khaledi Alidusti, R ; Sabouri, M ; Schneider, G. E ; Sharif University of Technology
    We use three-dimensional molecular dynamics simulation to investigate the driven flow between two parallel plates separated by argon atoms. Our simulations show that fluids in such channels can be continuously driven. Difference in surface wettability can cause a difference in fluid density along the nano channel. To control the nanochannel temperature walls, we use the thermal wall idea, which models the walls using atoms connected to their original positions by enforcing linear spring forces. In this study, we propose a nanochannel system in which, half of the channel has a low surface wettability, while the other half has a higher surface wettability and that the middle part of channel... 

    Surface wettability effect on the rising of a bubble attached to a vertical wall

    , Article International Journal of Multiphase Flow ; Volume 109 , 2018 , Pages 178-190 ; 03019322 (ISSN) Javadi, K ; Davoudian, S. H ; Sharif University of Technology
    This paper deals with the dynamics of rising bubbles attached to a vertical wall under different wettability conditions. Even though, bubbles rising freely in a liquid have extensively been studied, bubbles attached to a wall have not been fully understood. Therefore, in this work, rising bubbles attached to a vertical wall were numerically investigated by applying the ALE method along with adaptive mesh refinement schemes to properly resolve the bubble interface and its deformation. To consider wall wettability effects, different contact angles of 45° 90° and 105° were considered along with the case of freely rising bubbles. The problem was carried out at different Bond numbers of 0.27,... 

    The role of surface wettability on the heat transfer in liquid-liquid two-phase flow in a microtube

    , Article Physics of Fluids ; Volume 31, Issue 8 , 2019 ; 10706631 (ISSN) Moezzi, M ; Kazemzadeh Hannani, S ; Farhanieh, B ; Sharif University of Technology
    American Institute of Physics Inc  2019
    Liquid-liquid two-phase flow is capable of boosting heat transfer in microdevices compared to the single-phase and gas-liquid flows. A thorough investigation is performed here to characterize the heat transfer in water-oil flow in a microtube. Finite element method along with the level-set model is employed for numerical simulation. A main part of this paper is devoted to studying the effect of wettability on the heat transfer performance. Four contact angles of 0°, 30°, 150°, and 180° are investigated, which revealed that the contact angle of 150° produces the highest Nusselt number (Nu). Triple points form at this contact angle, and the slugs slide on the wall, which results in more... 

    Nano-coated condensation surfaces enhanced the productivity of the single-slope solar still by changing the condensation mechanism

    , Article Journal of Cleaner Production ; Volume 265 , 2020 Zanganeh, P ; Soltani Goharrizi, A ; Ayatollahi, S ; Feilizadeh, M ; Sharif University of Technology
    Elsevier Ltd  2020
    Solar stills are considered an environmentally friendly technique to produce fresh water. The condensation surface plays an essential role in controlling the efficiency of the solar still. This main parameter is critically affected by the wettability of the condensation surface that affects the condensation mechanism, namely drop-wise or film-wise condensation. This study aims to enhance the efficiency of solar stills by altering the surface wettability hence changing the condensation mechanism using nanomaterials. In this experimental work, different condensation surfaces were coated by silicone nanoparticles to change the condensation mechanism from film to dropwise. Scanning electron... 

    Coarsening dynamics of nanodroplets on topographically structured substrates

    , Article Journal of Physics Condensed Matter ; Volume 25, Issue 4 , 2013 ; 09538984 (ISSN) Asgari, M ; Moosavi, A ; Sharif University of Technology
    Employing a biharmonic boundary integral method with linear elements, coarsening dynamics of nanodroplets on topographical step heterogeneity is investigated. It is shown that the step height and droplet configuration have an influential effect on the dynamics. Increasing the step height slows down the process while locating the droplets close to the step boosts the coarsening rate. Considering a slip boundary condition enhances the dynamics and reveals a transition in the droplet migration direction. Our results reveal that increasing the surface wettability weakens the dynamics. Various types of the disjoining pressure over the step are also considered and their effects on the coarsening... 

    Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study

    , Article Applied Energy ; Volume 268 , 2020 Zanganeh, P ; Soltani Goharrizi, A ; Ayatollahi, S ; Feilizadeh, M ; Dashti, H ; Sharif University of Technology
    Elsevier Ltd  2020
    The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to... 

    Pore-Scale Monitoring of Wettability Alteration by Silica Nanoparticles During Polymer Flooding to Heavy Oil in a Five-Spot Glass Micromodel

    , Article Transport in Porous Media ; Volume 87, Issue 3 , 2011 , Pages 653-664 ; 01693913 (ISSN) Maghzi, A ; Mohebbi, A ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in... 

    Wettability alteration in carbonates during "Smart Waterflood": Underling mechanisms and the effect of individual ions

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 487 , 2015 , Pages 142-153 ; 09277757 (ISSN) Rashid, S ; Mousapour, M. S ; Ayatollahi, S ; Vossoughi, M ; Beigy, A. H ; Sharif University of Technology
    Elsevier  2015
    There are increasing evidences that adjusting the chemistry of the injecting water improves the oil recovery efficiency. However, the underlying mechanisms for this technique which is referred to as "smart waterflood" have not yet been thoroughly understood. It is needed to explore the role of individual ions through set of different tests, to find the right mechanisms behind "smart waterflood". This study is focused on the fluid/solid (carbonate) interactions through systematic wettability measurement. Contact angle measurements accompanied by spontaneous imbibition tests were employed to determine the role of individual monovalent and divalent ions in wettability alteration process by... 

    Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

    , Article Materials Science and Engineering C ; Volume 29, Issue 4 , 2009 , Pages 1491-1497 ; 09284931 (ISSN) Ramezani Saadat Abadi, A ; Mousavi, A ; Seyedjafari, E ; Poursalehi, R ; Sareh, S ; Silakhori, K ; Poorfatollah, A. A ; Shamkhali, A. N ; Sharif University of Technology
    Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after...