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    Drop formation from a capillary tube: comparison of different bulk fluid on newtonian drops and formation of newtonian and non-newtonian drops in air using image processing

    , Article International Journal of Heat and Mass Transfer ; Volume 124 , 2018 , Pages 912-919 ; 00179310 (ISSN) Nazari, A ; Zadkazemi Derakhshi, A ; Nazari, A ; Firoozabadi, B ; Sharif University of Technology
    The formation of water drops as a Newtonian fluid and formation of a shear-thinning non-Newtonian fluid, Carboxyl Methyl Cellulose (CMC) from a capillary into different bulk fluids are experimentally investigated. A high speed camera is used to visualize the images of the drops and an image-processing code employed to determine the drop properties from each image. It was found that the properties of the water drops when they are drooped into the liquids bulk fluids such as toluene and n-hexane are almost the same while they differed substantially when they were drooped into the air bulk fluid. It is shown that during the formation of water drop in all three kinds of bulk fluids, the drop... 

    DPD simulation of electroosmotic flow in nanochannels and the evaluation of effective parameters

    , Article 10th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, 28 June 2010 through 1 July 2010, Chicago, IL ; 2010 ; 9781600867453 (ISBN) Darbandi, M ; Zakeri, R ; Schneider, G. E ; Sharif University of Technology
    We provide the simulation of electroosmotic phenomenon in nanochannels using the Dissipative Particle Dynamics (DPD) method. We study the electroosmotic phenomenon for both newtonian and non-newtonian fluids. Literature shows that most of past electroosmotic studies have been concentrated on continuum newtonian fluids. However, there are many nano/microfluidic applications, which need to be treated as either non-newtonian fluids or non-continuum fluids. In this paper, we simulate the electroosmotic flow in nanochannel considering no limit if it is neither continuum nor non-nonewtonian. As is known, the DPD method has several important advantages compared with the classical molecular dynamics... 

    On the motion of Newtonian and non-Newtonian liquid drops

    , Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1265-1278 ; 10263098 (ISSN) Aminzadeh, M ; Maleki, A ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
    In the present study, the motion of Newtonian and non-Newtonian liquid drops has been investigated experimentally. In order to investigate the effect of bulk fluid on drops, we have used water and air, as two fluids with different properties, and various industrial and biological applications. Image processing is utilized to analyze the images obtained by a high speed camera. The research has been separated into two parts. The first part has been devoted to the experiments in which air is the bulk fluid, and the second is related to the experiment carried out in water. The range of Reynolds number is, approximately, 50

    Electric-field-induced response of a droplet embedded in a polyelectrolyte gel

    , Article Physics of Fluids ; Volume 25, Issue 8 , 2013 ; 10706631 (ISSN) Mohammadi, A ; Sharif University of Technology
    The electric-field induced response of a droplet embedded in a quenched polyelectrolyte gel is calculated theoretically. The response comprises the droplet translation and the electric-field induced flow fields within the droplet. The gel is modeled as a soft, and electrically charged porous solid saturated with a salted Newtonian fluid. The droplet is considered an incompressible Newtonian fluid with no free charge. An analytical solution, using the perturbation methodology and linear superposition, is obtained for the leading-order steady response to a DC electric-field. The fluid within the droplet is driven due to hydrodynamic coupling with the electroosmotic flow. The fluid velocity... 

    DPD simulation of non-Newtonian electroosmotic fluid flow in nanochannel

    , Article Molecular Simulation ; Volume 44, Issue 17 , 2018 , Pages 1444-1453 ; 08927022 (ISSN) Jafari, S ; Zakeri, R ; Darbandi, M ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    We use the dissipative particle dynamics (DPD) method to simulate the non-Newtonian electroosmotic flow (EOF) through nanochannels. Contrary to a large amount of past computational efforts dedicated to the study of EOF profile, this work pays attention to the EOF of non-Newtonian fluids, which has been rarely touched in past publications. Practically, there are many MEMS/NEMS devices, in which the EOF behaviour should be treated assuming both non-continuum and non-Newtonian conditions. Therefore, our concern in this work is to simulate the EOF through nanochannels considering both non-Newtonian fluid properties and non-continuum flow conditions. We have chosen DPD as our working tool because... 

    Modelling of generalized newtonian lid-driven cavity flow using an SPH method

    , Article ANZIAM Journal ; Volume 49, Issue 3 , 2008 , Pages 411-422 ; 14461811 (ISSN) Rafiee, A ; Sharif University of Technology
    In this paper a smoothed particle hydrodynamics (SPH) method is introduced for simulating two-dimensional incompressible non-Newtonian fluid flows, and the non-Newtonian effects in the flow of a fluid which can be modelled by generalized Newtonian constitutive equations are investigated. Two viscoplastic models including Bingham-plastic and power-law models are considered along with the Newtonian model. The governing equations include the conservation of mass and momentum equations in a pseudo-compressible form. The spatial discretization of these equations is achieved by using the SPH method. The temporal discretization algorithm is a fully explicit two-step predictorcorrector scheme. In... 

    Phase transition in modified newtonian dynamics (Mondian) self-gravitating systems

    , Article Entropy ; Volume 23, Issue 9 , 2021 ; 10994300 (ISSN) Zhoolideh Haghighi, M. H ; Rahvar, S ; Rahimi Tabar, M. R ; Sharif University of Technology
    MDPI  2021
    We study the statistical mechanics of binary systems under the gravitational interaction of the Modified Newtonian Dynamics (MOND) in three-dimensional space. Considering the binary systems in the microcanonical and canonical ensembles, we show that in the microcanonical systems, unlike the Newtonian gravity, there is a sharp phase transition, with a high-temperature homogeneous phase and a low-temperature clumped binary one. Defining an order parameter in the canonical systems, we find a smoother phase transition and identify the corresponding critical temperature in terms of the physical parameters of the binary system. © 2021 by the authors. Licensee MDPI, Basel, Switzerland  

    Controlled drug delivery using the magnetic nanoparticles in non-Newtonian blood vessels

    , Article Alexandria Engineering Journal ; 2020 Abu Hamdeh, N. H ; Bantan, R. A. R ; Aalizadeh, F ; Alimoradi, A ; Sharif University of Technology
    Elsevier B.V  2020
    Fouling in blood flow is very common and may decrease the blood flow in human body and lead to critical health issues. Upon injury in a blood vessel, the body's defensive system triggers a process to create a blood clot called “Thrombus”, which prevents bleeding. Blood clots are formed by a combination of blood cells, platelets, and fibrins. In this study, we investigate a controlled drug delivery using the magnetic nanoparticles in blood vessels under the influence of magnetic fields. For this purpose the Maxwell and the Navier-Stokes equations for the system are solved. In contrary to the previous studies it is assumed that the blood is a non-Newtonian fluid. The number of particles has... 

    Experimental investigation and comparison of Newtonian and non-Newtonian shear-thinning drop formation

    , Article Experimental Thermal and Fluid Science ; Volume 94 , 2018 , Pages 148-158 ; 08941777 (ISSN) Salehi, M. S ; Esfidani, M. T ; Afshin, H ; Firoozabadi, B ; Sharif University of Technology
    Elsevier Inc  2018
    The presence of small amount of polymer in Newtonian liquids affects the fluid behavior significantly and creates superficial differences between Newtonian and non-Newtonian drop formation. In the present study, Newtonian and non-Newtonian shear-thinning drop formation in air is examined experimentally and the geometrical parameters, such as drop elongation length, minimum neck diameter and current contact angle are studied for water, glycerin solutions (79, 89 and 94% w/w) and Carboxymethyl cellulose (CMC) solutions (0.5 to 1.5% w/w) drops. The results indicate that at initial stages of the drop growth, Newtonian and non-Newtonian liquids behave similarly. However, at the start of the... 

    Thermal transport characteristics of non-newtonian electroosmotic flow in a slit microchannel

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011 ; Volume 1 , June , 2011 , Pages 169-176 ; 9780791844632 (ISBN) Babaie, A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    Electroosmosis has many applications in fluid delivery at microscale, sample collection, detection, mixing and separation of various biological and chemical species. In biological applications, most fluids are known to be non-Newtonian. Therefore, the study of thermal features of non-Newtonian electroosmotic flow is of great importance for scientific communities. In the present work, the fully developed electroosmotic flow of power-law fluids in a slit microchannel is investigated. The related equations are transformed into non-dimensional forms and necessary changes are made to adapt them for non-Newtonian fluids of power-law model. Results show that depending on different flow parameters... 

    Computational inertial microfluidics: a review

    , Article Lab on a Chip ; Volume 20, Issue 6 , 2020 , Pages 1023-1048 Razavi Bazaz, S ; Mashhadian, A ; Ehsani, A ; Saha, S. C ; Krüger, T ; Ebrahimi Warkiani, M ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Since the discovery of inertial focusing in 1961, numerous theories have been put forward to explain the migration of particles in inertial flows, but a complete understanding is still lacking. Recently, computational approaches have been utilized to obtain better insights into the underlying physics. In particular, fundamental aspects of particle focusing inside straight and curved microchannels have been explored in detail to determine the dependence of focusing behavior on particle size, channel shape, and flow Reynolds number. In this review, we differentiate between the models developed for inertial particle motion on the basis of whether they are semi-analytical, Navier-Stokes-based,... 

    Enhanced oil-in-water droplet generation in a T-junction microchannel using water-based nanofluids with shear-thinning behavior: A numerical study

    , Article Physics of Fluids ; Volume 33, Issue 1 , 2021 ; 10706631 (ISSN) Besanjideh, M ; Shamloo, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
    American Institute of Physics Inc  2021
    Nanofluids are widely used as the continuous phase during droplet formation in microsystems due to their impressive features such as excellent thermal, magnetic, and interfacial properties. Although it is well-known that nanofluids are susceptible to exhibit non-Newtonian behavior even at a low concentration of nanoparticles, effects of non-Newtonian behavior of nanofluids have not been studied on droplet formation thus far. In this study, oil-in-water droplet formation with a relatively high viscosity ratio of the immiscible phases was studied numerically in a T-junction microchannel. To inspect the non-Newtonian effects of aqueous nanofluids on droplet formation, empirical data on the... 

    Molecular Dynamics Simulation of Electroosmotic Flow in Nano scales

    , M.Sc. Thesis Sharif University of Technology Zakeri, Ramin (Author) ; Darbandi, Masoud (Supervisor)
    Due to important applications and benefits of mass transfer in engineering and especially in nano-scales engineering, nano-science researchers have focused on this field. Considerably, in classical fluid dynamics applications, the fluid can be transported using differential pressure gradient. But the classical methods require moving components, which are usually expensive and not applicable in nano-sizes. To avoid these problems in nano-size transportation, we can use electro-osmotic process to perform mass transfer in low transfer rates. In electro-osmotic process, we can move electrolyte solvent with the aid of an external electrical field. Due to importance of this process in... 

    Saffman-Taylor instability in yield stress fluids

    , Article Journal of Physics Condensed Matter ; Volume 17, Issue 14 , 2005 , Pages S1209-S1218 ; 09538984 (ISSN) Maleki Jirsaraei, N ; Lindner, A ; Rouhani, S ; Bonn, D ; Sharif University of Technology
    Institute of Physics Publishing  2005
    Pushing a fluid with a less viscous one gives rise to the well known Saffman-Taylor instability. This instability is important in a wide variety of applications involving strongly non-Newtonian fluids that often exhibit a yield stress. Here we investigate the Saffmann-Taylor instability in this type of fluid, in longitudinal flows in Hele-Shaw cells. In particular, we study Darcy's law for yield stress fluids. The dispersion equation for the flow is similar to the equations obtained for ordinary viscous fluids but the viscous terms in the dimensionless numbers conditioning the instability now contain the yield stress. This also has repercussions on the wavelength of the instability as it... 

    An investigation on the body force modeling in a lattice Boltzmann BGK simulation of generalized Newtonian fluids

    , Article Physica A: Statistical Mechanics and its Applications ; Vol. 415, issue , 2014 , pp. 315-332 Farnoush, S ; Manzari, M. T ; Sharif University of Technology
    Body force modeling is studied in the Generalized Newtonian (GN) fluid flow simulation using a single relaxation time lattice Boltzmann (LB) method. First, in a shear thickening Poiseuille flow, the necessity for studying body force modeling in the LB method is explained. Then, a parametric unified framework is constructed for the first time which is composed of a parametric LB model and its associated macroscopic dual equations in both steady state and transient simulations. This unified framework is used to compare the macroscopic behavior of different forcing models. Besides, using this unified framework, a new forcing model for steady state simulations is devised. Finally, by solving a... 

    Electrophoretic velocity of spherical particles in Quemada fluids

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 436 , September , 2013 , Pages 225-230 ; 09277757 (ISSN) Moosavi, S. M ; Sadeghi, A ; Saidi, M. S ; Sharif University of Technology
    The biomicrofluidic devices utilizing electrophoresis for sample manipulation are usually encountered with non-Newtonian behavior of working fluids. Hence, developing theoretical models capable of predicting the electrophoretic velocity of colloidal particles in non-Newtonian fluids is of high importance for accurate design and active control of these devices. The present investigation is dealing with the electrophoresis of a spherical particle in a biofluid obeying the Quemada rheological model. The sphere radius is considered to be significantly larger than the Debye length. Moreover, it is assumed that the particle zeta potential is small so that the Debye-Hückel linearization is... 

    Numerical simulations of haemodynamic factors and hyperelastic Circumferential Strain/Stress in the ideal and healthy-patient-specific carotid bifurcations for different rheological models

    , Article International Journal of Biomedical Engineering and Technology ; Volume 6, Issue 4 , 2011 , Pages 387-412 ; 17526418 (ISSN) Toloui, M ; Nikparto, A ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    To explore the role of hemodynamic in the initiation and progression of stenosis in carotid artery bifurcation, a Computational Fluid Dynamics (CFD) technique is applied. The effect of four rheology models is investigated as well as various mechanical phenomena. In this study, a Finite Element Method (FEM) was applied to simulate the physiologic Circumferential Strain/Stress (CS) Meanwhile, to investigate the role of vessel wall flexibility, a Fluid-Structure Interaction (FSI) analysis was applied. It was concluded that velocity profiles and WSS show sensitivity to arterial wall stiffening while shear thinning models do not have a dominant effect on the flow field  

    A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

    , Article Microfluidics and Nanofluidics ; Volume 19, Issue 6 , 2015 , Pages 1297-1308 ; 16134982 (ISSN) Ahmadian Yazdi, A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    Springer Verlag  2015
    Both nonlinear rheology and finite EDL thickness effects on the mixing process in an electroosmotically actuated Y-sensor are being investigated in this paper, utilizing a depthwise averaging method based on the Taylor dispersion theory. The fluid rheological behavior is assumed to obey the power-law viscosity model. Analytical solutions are obtained assuming a large channel width to depth ratio for which a 1-D profile can efficiently describe the velocity distribution. Full numerical simulations are also performed to determine the applicability range of the analytical model, revealing that it is able to provide accurate results for channel aspect ratios of ten and higher and quite... 

    Modeling and experimental investigation of bubble formation in shear-thinning liquids

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 139, Issue 7 , 2017 ; 00982202 (ISSN) Taghi Esfidani, M ; Reza Oshaghi, M ; Afshin, H ; Firoozabadi, B ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2017
    This investigation presents both theoretical and experimental studies on the size of a growing bubble in power-law non-Newtonian liquids. At first, some previous works on the prediction of bubble size in Newtonian liquids have been extended by considering the balance of forces acting on the bubble at the moment of separation. Predicted bubble sizes were validated against the experimental results for a wide range of operating conditions, including different gas flow rates and needle diameters as well as a wide range of physical properties of the Newtonian liquids. Furthermore, in order to determine the size of the bubbles formed in power-law non-Newtonian liquids with a similar analysis, the... 

    Transient analysis of falling cylinder in non-Newtonian fluids: further opportunity to employ the benefits of SPH method in fluid-structure problems

    , Article Chemical Product and Process Modeling ; Volume 12, Issue 1 , 2017 ; 21946159 (ISSN) Kamyabi, M ; Ramazani Saadat Abadi, A ; Kamyabi, A ; Sharif University of Technology
    Walter de Gruyter GmbH  2017
    Smoothed particle hydrodynamics (SPH) was applied to simulate the free falling of cylindrical bodies in three types of fluids including Newtonian, generalized-Newtonian and viscoelastic fluids. Renormalized derivation schemes were used because of their consistency in combination with the latest version of no slip boundary condition to improve the handling of moving fluid-structure interactions (FSIs). Verification of the method was performed through comparing the results of some benchmark examples for both single and two phase flows with the literature. The effects of some parameters such as the viscosity of the Newtonian fluid, the n index of the power-law fluid and the relaxation time of...