Browsing by Subject "Thermo-physical property"

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    Evaluation of nusselt number for a flow in a microtube with second-order model including thermal creep
    (ASME, 2012-07) Çetin, Barbaros
    In this paper, Nusselt number for a flow in a microtube is determined analytically with a constant wall heat flux thermal boundary condition. The flow assumed to be incompressible, laminar, hydrodynamically and thermally fully-developed. The thermo-physical properties of the fluid are assumed to be constant. The effect of rarefaction, viscous dissipation, axial conduction, which are important at the microscale, are included in the analysis. For the implementation of the rarefaction effect, two different second-order slip models are used for the slip-flow and temperature-jump boundary conditions together with the thermal creep at the wall. Closed form solutions for the fully-developed temperature profile and Nusselt number are derived as a function of Knudsen number, Brinkman number and Peclet number. Copyright © 2012 by ASME.
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    Modeling of evaporation from a sessile constant shape droplet
    (ASME, 2017) Akkuş, Y.; Çetin, Barbaros; Dursunkaya, Z.
    In this study, a computational model for the evaporation from a sessile liquid droplet fed from the center to keep the diameter of the droplet constant is presented. The continuity, momentum and energy equations are solved with temperature dependent thermo-physical properties using COMSOL Multi-physics. At the surface of the droplet, convective heat and evaporative mass fluxes are assigned. Since the flow field is affected by evaporative flux, an iterative scheme is built and the computation is automated using COMSOL-MATLAB interface. Correlations are implemented to predict the convective heat transfer coefficients and evaporative flux. Three different wall temperatures are used in simulations. The results show that the flow inside the droplet is dominated by buoyancy when the effect of the thermo-capillarity is neglected. The resulting flow generates a circulation pattern emerging from the entrance to the apex, along the surface of the droplet to the bottom heated wall and back to the entrance.