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    A compressible flow solver for high Thermobuoyant flow fields

    , Article 37th AIAA Thermophysics Conference 2004, Portland, OR, 28 June 2004 through 1 July 2004 ; 2004 ; 9781624100352 (ISBN) Darbandi, M ; Schneider, G. E ; Hosseinizadeh, S. F ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2004
    Abstract
    The use of classical Bossiness approximation is a straightforward strategy to take into account the buoyancy effect in incompressible solvers. This strategy is highly effective if the density variation is low. However, ignoring the importance of density variation in high thermo buoyant flows can cause considerable deviation in predicting the correct fluid flow behavior and heat transfer phenomenon. Indeed, there are many technological and environmental problems where the Bossiness approximation is not valid. In this study, an incompressible algorithm is suitably extended in order to solve compressible flow problems with natural-convection heat transfer. In this regard, the density field is... 

    The step effect and particle removal from an enclosure

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Hendijanifard, M ; Saidi, M. H ; Taeibi Rahni, M ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    Abstract
    This paper reports the results of a study of the transient removal of contaminant particle from enclosures containing an obstacle. We study specially a phenomena occur sometimes called the step effect. This phenomenon may occur if the size of the obstacle is small enough in comparison with the length or height of the enclosure. These results are the basic instruments for finding a model for contaminant particle removal from an enclosure containing an obstacle. A numerical CFD code is developed and validated with different cases, and then proper two- and three-dimensional cases are modeled. The size of the obstacle affect the order of magnitude of the convection-diffusion terms in the... 

    Darcy model for the study of the fluid flow and heat transfer around a cylinder embedded in porous media

    , Article International Journal for Computational Methods in Engineering Science and Mechanics ; Volume 7, Issue 5 , 2006 , Pages 323-329 ; 15502287 (ISSN) Layeghi, M ; Nouri Borujerdi, A ; Sharif University of Technology
    Taylor and Francis Inc  2006
    Abstract
    Steady-state convective heat transfer around a circular cylinder embedded in porous media is studied in the range of low and moderate Peclet numbers less than 40. The cylinder is at constant temperature and the Darcy model is used for the analysis of fluid flow and heat transfer in porous media. The governing equations are discretised using finite volume approach based on staggered grids. The powerlaw scheme is used in the numerical solution and a SIMPLE-like algorithm is developed and used in the solution process. It is found that the numerical algorithm is sufficiently efficient in the range of Peclet numbers less than 40. Parametric studies are done for better understanding of the porous... 

    Gaseous slip flow forced convection in microducts of arbitrary but constant cross section

    , Article Nanoscale and Microscale Thermophysical Engineering ; Vol. 18, issue. 4 , 2014 , p. 354-372 Baghani, M ; Sadeghi, A ; Sharif University of Technology
    Abstract
    This is a theoretical study that extends a classical method of treating the convection heat transfer in complex geometries to gaseous slip flow forced convection in microchannels with H1 thermal boundary condition. Through this line, the momentum and energy equations in cylindrical coordinates are made dimensionless. Afterward, solutions are presented that exactly satisfy the dimensionless differential equations along with the symmetry condition and finiteness of the flow parameter at the origin. The first-order slip boundary conditions are then applied to the solution utilizing the least squares matching method. Though the method is general enough to be applied to almost any arbitrary cross... 

    Joule heating effects in electrokinetically driven flow through rectangular microchannels: An analytical approach

    , Article Nanoscale and Microscale Thermophysical Engineering ; Volume 17, Issue 3 , 2013 , Pages 173-193 ; 15567265 (ISSN) Sadeghi, A ; Kazemi, Y ; Saidi, M. H ; Sharif University of Technology
    2013
    Abstract
    This is a theoretical study dealing with mixed electroosmotic and pressure-driven flow of a Newtonian liquid in a rectangular microchannel. Both and thermal boundary conditions are considered and the Debye-Hückel linearization is invoked. The governing equations are made dimensionless assuming fully developed conditions and then analytically solved using an infinite series solution. The governing factors are found to be the dimensionless Debye-Hückel parameter, velocity scale ratio, dimensionless Joule heating parameter, and channel aspect ratio. The results indicate that the Nusselt number is an increasing function of the channel aspect ratio, whereas the opposite is true for the velocity... 

    Gaseous slip flow forced convection through ordered microcylinders

    , Article Microfluidics and Nanofluidics ; Volume 15, Issue 1 , 2013 , Pages 73-85 ; 16134982 (ISSN) Sadeghi, A ; Baghani, M ; Saidi, M. H ; Sharif University of Technology
    2013
    Abstract
    This is a theoretical study dealing with longitudinal gaseous slip flow forced convection between a periodic bunch of microcylinders arranged in regular array. The selected geometry has applications in microscale pin fin heat sinks used for cooling of microchips. The flow is considered to be hydrodynamically and thermally fully developed. The two axially constant heat flux boundary conditions of H1 and H2 are considered in the analysis. The velocity and temperature discontinuities at the boundary are incorporated into the solutions using the first order slip boundary conditions. The method considered is mainly analytical in which the governing equations and three of the boundary conditions... 

    Series solution for heat transfer of continuous stretching sheet immersed in a micropolar fluid in the existence of radiation

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 23, Issue 2 , 2013 , Pages 289-304 ; 09615539 (ISSN) Shadloo, M. S ; Kimiaeifar, A ; Bagheri, D ; Sharif University of Technology
    2013
    Abstract
    Purpose - The purpose of this paper is to study a two-dimensional steady convective flow of a micropolar fluid over a stretching sheet in the presence of radiation with constant temperature. Design/methodology/approach - The corresponding momentum, microrotation and energy equations are analytically solved using homotopy analysis method (HAM). Findings - To validate the method, investigate the accuracy and convergence of the results, a comparison with existing numerical and experimental results is done for several cases. Finally, by using the obtained analytical solution, for the skin-friction coefficient and the local Nusselt number as well as the temperature, velocity and angular velocity,... 

    Performance optimization of solar chimney power plant using electric/corona wind

    , Article Journal of Electrostatics ; Volume 78 , 2015 , Pages 22-30 ; 03043886 (ISSN) Nasirivatan, S ; Kasaeian, A ; Ghalamchi, M ; Ghalamchi, M ; Sharif University of Technology
    Elsevier  2015
    Abstract
    The effect of the corona wind on the natural convection at absorber of a solar chimney power plant pilot was investigated experimentally. The aim of the study is to improve the efficiency of SCPP through enhanced the heat transfer coefficient of absorber with corona wind. The results show that corona wind enhanced the absorber convective heat transfer coefficient leading to increment in air the velocity and the output power of the SCPP. The amount of heat transfer of pilot increased more than 14.5% when applying voltage of 15 KV and the speed in chimney experienced about 72% amelioration  

    Two-dimensional free convection heat transfer below a horizontal hot isothermal flat strip

    , Article Journal of Heat Transfer ; Volume 137, Issue 5 , May , 2015 ; 00221481 (ISSN) Samie, M ; Nouri Gheimassi, A ; Salari, A ; Behshad Shafii, M ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2015
    Abstract
    Convection heat transfer below a horizontal, hot, and isothermal strip of infinite length and width of 2L embedded in fluids with different Prandtl number (Pr) and Nusselt number (Nu) is analyzed with the aid of integral method. A new concept is utilized to determine the boundary layer thickness at the strip's edge, which is based on matching the flow rate of the boundary layer below the strip at its edge and the flow rate of the plume, which forms after the heated fluid detaches from the strip's edge. In addition to these novelties, a numerical model is developed to verify the analytical framework, and an excellent agreement is observed between the analytical and numerical models  

    Heat transfer of swirling impinging jets ejected from Nozzles with twisted tapes utilizing CFD technique

    , Article Case Studies in Thermal Engineering ; Volume 6 , September , 2015 , Pages 104-115 ; 2214157X (ISSN) Amini, Y ; Mokhtari, M ; Haghshenasfard, M ; Barzegar Gerdroodbary, M ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    This research investigated the forced convection heat transfer by using the swirling impinging jets. This study focused on nozzles, which equipped with twisted tapes via a numerical approach. The computational domain created by utilizing the fully structured meshes, which had very high quality from the viewpoint of aspect ratio and skewness. The numerical simulations were performed at four different jet-to-plate distances (L/D) of 2, 4, 6 and 8, four Reynolds numbers of 4000, 8000, 12,000 and 16,000, and also four different twist ratios (y/w) of 3, 4, 5 and 6. The mesh-independent tests were conducted based upon the average Nusselt number. The obtained results revealed good agreement with... 

    Flow fields investigation and temperature distribution on a rotating disk imposed by a turbulent impinging jet

    , Article 2010 14th International Heat Transfer Conference, IHTC 14, 8 August 2010 through 13 August 2010, Washington, DC ; Volume 5 , 2010 , Pages 719-725 ; 9780791849408 (ISBN) Karrabi, H ; Rasoulipour, S ; Sharif University of Technology
    2010
    Abstract
    Numerical investigation of fluid flow structure and convective heat transfer due to a circular jet impinging on a rotating disk is performed. Temperature and convection heat transfer coefficient are calculated. Flow is considered to be steady, incompressible and turbulent. k-ε RNG model is used to model the turbulent flow. Results are compared with experimental data showing good agreement. Two new criteria are introduced and used to evaluate the performance of cooling process, the first is maximum temperature difference on the disk, and the second is the average temperature of the disk. The first parameter shows the uniformity of temperature distribution in the disk and the second shows the... 

    Experimental assessment of convective heat transfer coefficient enhancement of nanofluids prepared from high surface area nanoporous graphene

    , Article International Communications in Heat and Mass Transfer ; Volume 78 , 2016 , Pages 127-134 ; 07351933 (ISSN) Naghash, A. S ; Sattari, S ; Rashidi, A. M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    In this research convective heat transfer coefficient enhancement of nanofluids prepared from high surface area graphene has been investigated in laminar flow in the developing region. The nanofluid has been prepared from nanoporous graphene with high surface area and with concentration of 0.025 to 0.1 wt.%. Deionized water has been used as the base fluid and a type of Ter-Polymer has been utilized as the surfactant. The results indicate that thermal conductivity of nanofluid with concentration of 0.1 wt.% remains quite constant, with only 3.8% enhancement, while convective heat transfer coefficient improves significantly, with 34% enhancement. The behavior of this enhancement related to the... 

    Simulation of thermally developing laminar ow in partially filled porous pipes under wall suction

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2641-2649 ; 10263098 (ISSN) Nouri Borujerdi, A ; Seyyed Hashemi, M. H ; Sharif University of Technology
    Sharif University of Technology 
    Abstract
    This study numerically investigates uid ow and heat transfer enhancement of a two-dimensional developing laminar ow in an axisymmetric pipe with partially filled porous material attached to the wall. The effects of porous layer in the range of 0 ≤ δ=R < 1 and Darcy number in the range of 10-6 ≤ Da ≤ 10-4 are investigated. It is found that thermal entrance length increases with porous layer thickness and is longer than a plain pipe. In addition, the dependence of Nusselt number on the thickness of the porous layer is not monotonic. A critical value of the porous layer thickness exists at which the Nusselt number value reaches the minimum. As the porous layer is thickening, more uid is pushed... 

    Numerical simulation of magnetic convection ferrofluid flow in a permanent magnet–inserted cavity

    , Article Journal of Magnetism and Magnetic Materials ; Volume 442 , 2017 , Pages 270-278 ; 03048853 (ISSN) Ashouri, M ; Behshad Shafii, M ; Sharif University of Technology
    Abstract
    The magnetic convection heat transfer in an obstructed two-dimensional square cavity is investigated numerically. The walls of the cavity are heated with different constant temperatures at two sides, and isolated at two other sides. The cavity is filled with a high Prandtl number ferrofluid. The convective force is induced by a magnetic field gradient of a thermally insulated square permanent magnet located at the center of the cavity. The results are presented in the forms of streamlines, isotherms, and Nusselt number for various values of magnetic Rayleigh numbers and permanent magnet size. Two major circulations are generated in the cavity, clockwise flow in the upper half and... 

    An experimental comparison of SiO2/water nanofluid heat transfer in square and circular cross-sectional channels

    , Article Journal of Thermal Analysis and Calorimetry ; 2017 , Pages 1-10 ; 13886150 (ISSN) Pourfayaz, F ; Sanjarian, N ; Kasaeian, A ; Razi Astaraei, F ; Sameti, M ; Nasirivatan, S ; Sharif University of Technology
    Springer Netherlands  2017
    Abstract
    In this paper, with the aim of enhancing the thermal conductivity of the fluid, a nanofluid is prepared based on SiO2. A series of experimental tests were carried out for both laminar and forced convection regimes in a horizontal tube with two different geometric shapes (circular and square cross section) subjected to constant wall heat flux (4735 W m−2). A comparative study has been done to investigate the effect of the geometry on the convective heat transfer. Moreover, the effect of the volume concentration on the behavior of the nanofluid and the base fluid was evaluated by comparing various volume concentrations (0.05, 0.07 and 0.2%). The experiments were done under two different... 

    An experimental study on the proper criterion to judge the thermal performance of the nanofluids

    , Article International Communications in Heat and Mass Transfer ; Volume 82 , 2017 , Pages 20-28 ; 07351933 (ISSN) Sajedi, R ; Jafari, M ; Nasirivatan, S ; Osanloo, B ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    This work is dedicated to finding a suitable measure to judge thermal performance of nanofluids. The importance of this issue arises from misleading claim of excess heat transfer of nanofluids compared to the base fluid, neglecting the hydraulic effects such as increase in pressure drop. To clarify the issue, the experimental setup with capability to create constant Reynolds number and constant pumping power is constructed. Thermal behavior of nanofluids of silicon oxide/water and aluminum oxide/water and distilled water in developing region of laminar flow regime is investigated. In this regard, the convective heat transfer coefficient within the finned tube heat exchanger is evaluated.... 

    Modeling convective heat propagation in a fractured domain with x-fem and least square method

    , Article ASME 2017 International Mechanical Engineering Congress and Exposition, IMECE 2017, 3 November 2017 through 9 November 2017 ; Volume 8 , 2017 ; 9780791858431 (ISBN) Bahmani, B ; Khoei, A. R ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2017
    Abstract
    The main goal of the current study is developing an advanced and robust numerical tool for accurate capturing heat front propagation. In some applications such as impermeable medium, Heat transfer in the surrounding domain of fracture acts just as a conduction process but the heat transfer through the fractures appears as a convection process. From a mathematical point of view, a parabolic partial differential equation (PDE) should be solved in the surrounding domain whereas a hyperbolic PDE should be solved in the domain of fractures. In fact, they have completely different treatments and this is one of the complicated problems in this area. In this paper, the presence of fractures and... 

    Designing a polymerase chain reaction device working with radiation and convection heat transfer

    , Article 2017 International Conference on Nanomaterials and Biomaterials, ICNB 2017, 11 December 2017 through 13 December 2017 ; Volume 350, Issue 1 , 2018 ; 17578981 (ISSN) Madadelahi, M ; Kalan, K ; Shamloo, A ; Sharif University of Technology
    Institute of Physics Publishing  2018
    Abstract
    Gene proliferation is vital for infectious and genetic diseases diagnosis from a blood sample, even before birth. In addition, DNA sequencing, genetic finger-print analyzing, and genetic mutation detecting can be mentioned as other procedures requiring gene reproduction. Polymerase chain reaction, briefly known as PCR, is a convenient and effective way to accomplish this task; where the DNA containing sample faces three temperature phases alternatively. These phases are known as denaturation, annealing, and elongation/extension which in this study -regarding the type of the primers and the target DNA sequence- are set to occur at 95, 58, and 72 degrees of Celsius. In this study, a PCR device... 

    An experimental comparison of SiO2/water nanofluid heat transfer in square and circular cross-sectional channels

    , Article Journal of Thermal Analysis and Calorimetry ; Volume 131, Issue 2 , 2018 , Pages 1577-1586 ; 13886150 (ISSN) Pourfayaz, F ; Sanjarian, N ; Kasaeian, A ; Razi Astaraei, F ; Sameti, M ; Nasirivatan, S ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    In this paper, with the aim of enhancing the thermal conductivity of the fluid, a nanofluid is prepared based on SiO2. A series of experimental tests were carried out for both laminar and forced convection regimes in a horizontal tube with two different geometric shapes (circular and square cross section) subjected to constant wall heat flux (4735 W m−2). A comparative study has been done to investigate the effect of the geometry on the convective heat transfer. Moreover, the effect of the volume concentration on the behavior of the nanofluid and the base fluid was evaluated by comparing various volume concentrations (0.05, 0.07 and 0.2%). The experiments were done under two different... 

    A finite-volume ELLAM for non-linear flux convection-diffusion problems

    , Article International Journal of Non-Linear Mechanics ; Volume 44, Issue 2 , 2009 , Pages 129-136 ; 00207462 (ISSN) Fatehi, R ; Taghizadeh Manzari, M ; Kazemzadeh Hannani, S ; Sharif University of Technology
    2009
    Abstract
    In this paper, a modified finite-volume Eulerian-Lagrangian localized adjoint method (FVELLAM) extended for convection-diffusion problems with a non-linear flux function is introduced. Tracking schemes are discussed using viscous Burgers' equation. It is shown that in order to have smooth results, only the new time level values should be used in tracking process. Then, the proposed method is employed to study immiscible incompressible two-phase flows in porous media. Various one- and two-dimensional test cases involving internal sources and sinks are solved and accuracy of solution and performance of the method are investigated by comparing the results obtained using FVELLAM with those of...