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    Simulation of mixed electroosmotic/pressure-driven flows by utilizing dissipative particle dynamics

    , Article Microfluidics and Nanofluidics ; Vol. 17, issue. 1 , July , 2014 , pp. 199-215 ; ISSN: 16134982 Mehboudi, A ; Noruzitabar, M ; Mehboudi, M ; Sharif University of Technology
    Abstract
    In this paper, we present an extension of dissipative particle dynamics method in order to study the mixed electroosmotic/pressure-driven micro- or nano-flows. This method is based on the Poisson-Boltzmann equation and has a great potential to resolve the electric double layer (EDL). Hence, apart from studying the bulk flow, it also provides a strong capability in order to resolve the complex phenomena occur inside the EDL. We utilize the proposed method to study the pure electroosmotic and also the mixed electroosmotic/pressure-driven flow through the straight micro-/nano-channels. The obtained results are in good agreement with the available analytical solutions. Furthermore, we study the... 

    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... 

    Graetz problem extended to mixed electroosmotically and pressure-driven flow

    , Article Journal of Thermophysics and Heat Transfer ; Volume 26, Issue 1 , 2012 , Pages 123-133 ; 08878722 (ISSN) Sadeghi, A ; Veisi, H ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
    2012
    Abstract
    Thermally developing mixed electroosmotically and pressure-driven flow in a parallel plate microchannel with a step change in wall temperature is considered in the framework of an extended Graetz problem. Both Joule heating and viscous dissipation effects are taken into consideration. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the associated eigenvalue problem is solved numerically. Nevertheless, an analytical solution is also presented for axial locations close to the entrance. Comparisons are made between the present results and those obtained by approximating the electroosmotic velocity with the... 

    Mixed electroosmotically and pressure-driven flow with temperature- dependent properties

    , Article Journal of Thermophysics and Heat Transfer ; Volume 25, Issue 3 , Sep , 2011 , Pages 432-442 ; 08878722 (ISSN) Sadeghi, A ; Yavari, H ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
    2011
    Abstract
    The present work reports the outcome of a comprehensive parametric study on mixed electroosmotically and pressure-driven flow in slit microchannels with constant wall heat fluxes. Special attention is given to disclose the applicability ranges of usual assumptions in simplified analyses. The governing equations for fully developed conditions are first made dimensionless and then solved by means of an implicit finite difference method. The results reveal that the assumption of constant thermophysical properties does not leadto significant errors in practical applications. Although the Debye-Huckel linearization may successfully be used to evaluate velocity profiles up to the zeta potentials... 

    Numerical simulation of heat transfer in mixed electroosmotic pressure-driven flow in straight microchannels

    , Article Journal of Thermal Science and Engineering Applications ; Volume 8, Issue 2 , 2016 ; 19485085 (ISSN) Shamloo, A ; Merdasi, A ; Vatankhah, P ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2016
    Abstract
    This paper investigates two-dimensional, time-independent elecroosmotic pressuredriven flow generated by a direct current electric potential with asymmetrical and symmetrical zeta potential distributions along the microchannel walls. Fluid flow through the horizontal microchannel is simulated using a numerical method. Two different cases are proposed to study the effect of electric potential on the flow field. First, negative electric potential is applied on the microchannel walls. In this case, large segments with negative electric potential are initially placed on the first half of the microchannel walls with two different arrangements. Afterward, smaller segments with negative electric... 

    Electroosmotic flow of power-law fluids with temperature dependent properties

    , Article Journal of Non-Newtonian Fluid Mechanics ; Volume 185-186 , 2012 , Pages 49-57 ; 03770257 (ISSN) Babaie, A ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Elsevier  2012
    Abstract
    The influence of variable fluid properties on mixed electroosmotic and pressure driven flow of non-Newtonian fluids is investigated in this paper. The non-linear coupled energy and momentum equations are solved by means of an iterative numerical approach. The results reveal that the temperature dependent effects only become significant at very high values of the Debye-Hückel parameter in case of combined electroosmotic and pressure driven flow and could safely be neglected in other cases. It is observed that the physical properties variation lead to a higher mean velocity in case of pressure assisted flow and a lower mean velocity in case of pressure opposed flow. Furthermore, the... 

    Hydrodynamic and thermal characteristics of combined electroosmotic and pressure driven flow in a microannulus

    , Article Journal of Heat Transfer ; Volume 134, Issue 10 , 2012 ; 00221481 (ISSN) Yavari, H ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    ASME  2012
    Abstract
    The present study considers both the hydrodynamic and thermal characteristics of combined electroosmotic and pressure driven flow in a microannulus. Analytical solutions are presented using the Debye-Hückel linearization along with the uniform Joule heating and negligible viscous dissipation assumptions, whereas exact results are achieved numerically. Here, the range of validity for the Debye-Hückel linearization is found to be about two times of that for a parallel plate microchannel. Accordingly, this linearization may successfully be used to evaluate the potential and velocity distributions up to the zeta potentials of 100 mV, provided that the dimensionless Debye-Hückel parameter is... 

    Heat transfer characteristics of mixed electroosmotic and pressure driven flow of power-law fluids in a slit microchannel

    , Article International Journal of Thermal Sciences ; Volume 53 , 2012 , Pages 71-79 ; 12900729 (ISSN) Babaie, A ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    2012
    Abstract
    Thermal transport characteristics of electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit microchannel are studied in this paper. Considering a fully developed flow with a constant wall heat flux as the boundary condition, the governing equations are numerically solved by means of the finite difference method. A complete parametric study is done in order to investigate the effects of different flow parameters on the thermal behaviors of the flow. The results show that the non-Newtonian characteristic of the fluid can influence the thermal behaviors of the flow by affecting the rate of heat convection and viscous dissipation; however, its influence... 

    Combined electroosmotically and pressure driven flow of power-law fluids in a slit microchannel

    , Article Journal of Non-Newtonian Fluid Mechanics ; Volume 166, Issue 14-15 , August , 2011 , Pages 792-798 ; 03770257 (ISSN) Babaie, A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    2011
    Abstract
    Electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit is analyzed. After numerically solving the Poisson-Boltzmann equation, the momentum equation with electroosmotic body force is solved through an iterative numerical procedure for both favorable and adverse pressure gradients. The results reveal that, in case of pressure assisted flow, shear-thinning fluids reach higher velocity magnitudes compared with shear-thickening fluids, whereas the opposite is true when an adverse pressure gradient is applied. The Poiseuille number is found to be an increasing function of the dimensionless Debye-Hückel parameter, the wall zeta potential, and the flow behavior... 

    Tuning the dispersion of reactive solute by steady and oscillatory electroosmotic-Poiseuille flows in polyelectrolyte-grafted micro/nanotubes

    , Article Journal of Fluid Mechanics ; 2019 , Pages 73-112 ; 00221120 (ISSN) Reshadi, M ; Saidi, M. H ; Sharif University of Technology
    Cambridge University Press  2019
    Abstract
    This paper extends the analysis of solute dispersion in electrohydrodynamic flows to the case of band broadening in polyelectrolyte-grafted (soft) capillaries by accounting for the effects of ion partitioning, irreversible catalytic reaction and pulsatile flow actuation. In the Debye-Hückel limit, we present the benchmark solutions of electric potential and velocity distribution pertinent to steady and oscillatory mixed electroosmotic-pressure-driven flows in soft capillaries. Afterwards, the mathematical models of band broadening based on the Taylor-Aris theory and generalized dispersion method are presented to investigate the late-time asymptotic state and all-time evolution of... 

    Tuning the dispersion of reactive solute by steady and oscillatory electroosmotic-Poiseuille flows in polyelectrolyte-grafted micro/nanotubes

    , Article Journal of Fluid Mechanics ; 2019 , Pages 73-112 ; 00221120 (ISSN) Reshadi, M ; Saidi, M. H ; Sharif University of Technology
    Cambridge University Press  2019
    Abstract
    This paper extends the analysis of solute dispersion in electrohydrodynamic flows to the case of band broadening in polyelectrolyte-grafted (soft) capillaries by accounting for the effects of ion partitioning, irreversible catalytic reaction and pulsatile flow actuation. In the Debye-Hückel limit, we present the benchmark solutions of electric potential and velocity distribution pertinent to steady and oscillatory mixed electroosmotic-pressure-driven flows in soft capillaries. Afterwards, the mathematical models of band broadening based on the Taylor-Aris theory and generalized dispersion method are presented to investigate the late-time asymptotic state and all-time evolution of... 

    Deriving an analytical model for hydro-magnetic micro flow controller

    , Article 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, Darmstadt, 23 June 2008 through 25 June 2008 ; Issue PART B , June , 2008 , Pages 1139-1146 ; 0791848345 (ISBN); 9780791848340 (ISBN) Esmaily Moghadam, M ; Shafii, M. B ; ASME ; Sharif University of Technology
    2008
    Abstract
    Fluid control, namely pumping and valving, is a critical factor in the performance of micro-fluidic systems. In recent years a variety of micro-fluidic systems are developed for the purpose of miniaturizing fluid handling, and chemical analysis to develop Lab On a Chip (LOC) technology. The mentioned facts resulted in design and fabrication of a novel hydromagnetic flow controller. The idea behind this device is that magnetic particles, mixed and dispersed in a carrier liquid, can be accumulated in the form of a piston. Depending upon dragging speed of these pistons, which itself is a function of switching time, this device can be used to either increase (pumping) or decrease (valving) the... 

    Variational formulation on Joule heating in combined electroosmotic and pressure driven microflows

    , Article International Journal of Heat and Mass Transfer ; Volume 61, Issue 1 , June , 2013 , Pages 254-265 ; 00179310 (ISSN) Sadeghi, A ; Saidi, M. H ; Waezi, Z ; Chakraborty, S ; Sharif University of Technology
    2013
    Abstract
    The present study attempts to analyze the extended Graetz problem in combined electroosmotic and pressure driven flows in rectangular microchannels, by employing a variational formulation. Both the Joule heating and axial conduction effects are taken into consideration. Since assuming a uniform inlet temperature profile is not consistent with the existence of these effects, a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. The method of analysis considered here is primarily analytical, in which series solutions are presented for the electrical potential, velocity, and temperature. For general treatment of the eigenvalue problem... 

    Combined influences of viscous dissipation, non-uniform Joule heating and variable thermophysical properties on convective heat transfer in microtubes

    , Article International Journal of Heat and Mass Transfer ; Volume 55, Issue 4 , January , 2012 , Pages 762-772 ; 00179310 (ISSN) Yavari, H ; Sadeghi, A ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
    Abstract
    This study presents a comprehensive investigation on hydrodynamic and thermal transport properties of mixed electroosmotically and pressure driven flow in microtubes. Particular emphasis is given to investigating the combined consequences of viscous dissipation, non-uniform Joule heating, and variable thermophysical properties. Analytical solutions are obtained using the Debye-Hückel linearization and constant fluid properties assumption, while a numerical solution is presented for variable fluid properties and non-uniform distribution of Joule heating. The results indicate that, viscous heating effect is pronounced significantly when a favorable pressure gradient exists and cannot be... 

    Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water

    , Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) Esmaily Moghadam, M ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
    2009
    Abstract
    The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...