Search for: suspensions--fluids
Total 57 records
Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Firoozabadi, B ; Ghasvari Jahromi, H ; Afshin, H ; Sharif University of Technology
Dense underflows are continuous currents, which move down the slope due to the fact that, their density are heavier than ambient water. In turbidity currents the density differences arises from suspended solids. Vicinity of the wall make density currents and wall jets similar in some sense but Variation of density cause this flows more complex than wall jets. An improved form of 'near-wall' k-ε turbulence model is chosen which preserve all characteristics of both density and wall jet currents and a compression is made between them. Then the outcomes from low Reynolds number k-ε model is compared with v2̄-f model which show similarity. Also results show good agreement with experimental data...
Article Journal of Physics Condensed Matter ; Volume 16, Issue 15 , 2004 , Pages 2497-2505 ; 09538984 (ISSN) ; Ghane Motlagh, B ; Baradaran, S ; Shekarian, E ; Rouhani, S ; Sharif University of Technology
Patterns formed by the flow of an inhomogeneous fluid (suspension) over a smooth inclined surface were studied. It was observed that fractal patterns form. There exists a threshold angle for the inclination above which global fractal patterns are formed. This angle depends on the particle size of the suspension. We observed that there are two fractal dimensions for these patterns, depending on the area from which the pattern is extracted. If the pattern is taken from the top which only consists of the beginning steps of the pattern forming, one finds two fractal dimensions, i.e. 1.35-1.45 and 1.6-1.7, in which the first one is dominant while, if the entire pattern is taken, then a fractal...
Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 292, Issue 2-3 , 2007 , Pages 99-109 ; 09277757 (ISSN) ; Zamankhan, P ; Mousavi, S. M ; Sharif University of Technology
The present effort is the development of a multiscale modeling, simulation methodology for investigating complex phenomena arising from flowing fiber suspensions. Specific consideration was given to dynamic simulations of viscoelastic fibers in which the fluid flow is predicted by a method that is a hybrid between Direct Numerical Simulations (DNS) and Large Eddy Simulation techniques (LES), and fluid fibrous structure interactions (FSI) will be taken into account. Numerical results are presented for which focus is on fiber floc deformation by hydrodynamic forces in turbulent flows. Dynamics of simple fiber networks in a shearing flow of water in a channel flow illustrate that the...
Article Chemical Engineering Science ; Volume 61, Issue 23 , 2006 , Pages 7565-7578 ; 00092509 (ISSN) ; Arefinia, R ; Sharif University of Technology
Sedimentation of particles can undermine the uniformity of the product in the manufacture of the particle-filled composites. An adequate mathematical description of the sedimentation process could be helpful for providing necessary information concerning the dominant parameters and can give an insight for the process designer to prevent such an undesirable phenomenon in composite production. The present article deals with the mathematical modeling of settling particles during curing of polymer matrix composites. The sedimentation process is described by the mass conservation law for particles. Since the viscosity of the suspending polymer increases as a result of curing process, a new model...
Article ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting ; 2014 ; ISBN: 9780791846278 ; Zabetian, M ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
Suspension flow has an important role in various applications such as paint, material and pharmaceutical industries. Settling is considered as a resisting phenomenon in the processes dealing with suspensions. Using nanoparticles as an additive to micro-particulates has been studied in limited studies. This work presents an experimental investigation to assess the effectiveness of nanoparticles in reduction of suspension settling. Microscopic imaging and transmission measurement were used to analyze the stability factors in a container. Transmission analysis revealed that presence of nanoparticles in the suspension, decreased the sedimentation rate. Microscopy showed that the settling rate...
Modeling of laser thermal and hydrodynamic effects on a dilute suspension of micro-particles in water, Article Journal of Mechanical Science and Technology ; Vol. 28, issue. 3 , 2014 , p. 1017-1026 ; Saidi, M. H ; Saidi, M. S ; Shafii, M. B ; Sharif University of Technology
Particle manipulation using laser beam is almost a new and contactless technique in particulate sciences. The method is based on the radiation pressure of light photons on the particles suspended in a semi-transparent fluid. Applications of the technique mainly cover microscopic separation and detection of biological objects. In this work, a theoretical study is conducted to investigate the hydrodynamic and thermal effects on a particulate flow in a mini-channel. Laser thermal effects are studied as a result of light absorption either in fluid or dispersed phase. An analytical model is developed to be the real simulator of a test bed developed by the authors. The main objective of performed...
Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 81, Issue 6 , Jun , 2010 ; 15393755 (ISSN) ; Jabbari Farouji, S ; Movahed, M. S ; Jafari, G. R ; Rahimi Tabar, M. R ; Sharif University of Technology
The existence of the important similarities between gelation and glass transition makes it hard to distinguish between the two types of nonergodic states experimentally. Here, we report on a stochastic analysis of the scattered light intensity through a colloidal particles suspension during the gel and glass formation. In this analysis, we exploit the methods developed for complex hierarchical systems, such as turbulence. Using the multiplicative log-normal cascade models, we provide a criterion to distinguish gels from glasses
Quasi-periodic and irregular motion of a solid sphere falling through a thixotropic yield-stress fluid, Article Applied Physics Express ; Volume 10, Issue 11 , 2017 ; 18820778 (ISSN) ; Maleki Jirsaraei, N ; Rouhani, S ; Bonn, D ; Sharif University of Technology
We report the observation of the oscillatory and irregular motion of solid spheres settling under the influence of gravity in a thixotropic yield-stress fluid, namely, a suspension of Laponite. The size of the ball and the aging time of the Laponite suspension are found to be two important parameters that determine whether oscillations occur. The irregular motion may be related to the existence of an unstable flow region and shear banding as is concluded from comparisons with rheological measurements, namely, the flow curve and creep tests, using the same Laponite suspensions. © 2017 The Japan Society of Applied Physics
Article Soft Matter ; Volume 13, Issue 25 , 2017 , Pages 4494-4506 ; 1744683X (ISSN) ; Kheyri, M ; Abazari, J ; Fahimniya, A ; Naji, A ; Sharif University of Technology
Royal Society of Chemistry 2017
We present a quantitative analysis on the response of a dilute active suspension of self-propelled rods (swimmers) in a planar channel subjected to an imposed shear flow. To best capture the salient features of the shear-induced effects, we consider the case of an imposed Couette flow, providing a constant shear rate across the channel. We argue that the steady-state behavior of swimmers can be understood in the light of a population splitting phenomenon, occurring as the shear rate exceeds a certain threshold, initiating the reversal of the swimming direction for a finite fraction of swimmers from down- to upstream or vice versa, depending on the swimmer position within the channel....
Fractal flow of inhomogeneous fluids over smooth inclined surfaces and determination of their fractal dimensions and universality classes, Article Journal of Physics Condensed Matter ; Volume 17, Issue 14 , 2005 , Pages S1219-S1227 ; 09538984 (ISSN) ; Ghane Motlagh, B ; Baradaran, S ; Shekarian, E ; Rouhani, S ; Sharif University of Technology
Patterns formed by the flow of an inhomogeneous fluid (suspension) over a smooth inclined surface were studied. It was observed that fractal patterns are formed. There exists a threshold angle for the inclination above which global fractal patterns are formed. This angle depends on the particle size of the suspension. We observed that there are two fractal dimensions for these patterns, depending on the area from which the pattern is extracted. If the pattern is taken from the top which only consists of the beginning steps of the pattern forming, one finds two fractal dimensions, i.e. 1.35-1.45 and 1.6-1.7, in which the first one is dominant. And if the entire pattern is taken, then fractal...
Effect of morphology-based defect structure of ZnO nanostructures in photo-degradation of organic dye, Article Materials Research Society Symposium Proceedings ; Vol. 1672 , 2014 ; ISSN: 02729172 ; Vosoughi, M ; Simchi, A ; Ghanbari, F ; Sharif University of Technology
The fabrication of strong photocatalysts applied to the degradation of organic pollutants is necessary in environmental applications. In a single-stage method, acetate precursor and poly vinyl pyrolydine are used to produce ZnO nanostructures with various morphologies in annealing temperatures ranging from 300 °C to 900 oC. The physical properties of the prepared nanostructures were characterized by SEM, XRD and PL spectroscopy. The SEM images exhibit a variety of the as-prepared hexagonal zinc oxides including wires, rods, particles and porous network of welded particles of ZnO nanoparticles. The results of the photocatalytic degradation of methylene blue as an organic dye in aqueous...
Article Journal of the European Ceramic Society ; Volume 33, Issue 10 , 2013 , Pages 1815-1823 ; 09552219 (ISSN) ; Yar, A. Y ; Vafaeenezhad, S ; Sani, M. A. F ; Simchi, A ; Sharif University of Technology
Functionally-graded NiO-8. mol % YSZ composite films were prepared by a controlled voltage-decay electophoretic deposition (EPD) process. The films consisted of three layers with varying NiO concentrations and porosities. Effects of different parameters including the type of the organic media, solid concentration, NiO:YSZ ratio, and iodine on the stability of EPD suspensions and deposition kinetics were studied. A stable NiO-YSZ suspension was attained in isopropanol with NiO-YSZ ratio of 60:40 and iodine concentration of 0.5. mM. The composite film contained varying NiO concentration from 46. wt.% near the substrate to 32. wt.% close to the electrolyte with 42. wt% NiO in the intermediate...
Article Carbohydrate Polymers ; Volume 93, Issue 2 , April , 2013 , Pages 506-511 ; 01448617 (ISSN) ; Fakoorpoor, S. M ; Hosseini, S. H ; Sharif University of Technology
A new cationic flocculant was synthesized by graft copolymerization of acrylamide (AM) and 3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) onto salep using free radical polymerization initiated by ammonium persulfate (APS) to produce cationic salep [S-g-P(AM-co-MAPTAC)]. Reaction parameters (monomers/salep ratio, concentration of reactants, MAPTAC/AM ratio, and APS) were optimized using a full factorial experimental design to obtain the highest settling rate for cement suspensions. The best performing product was characterized by gel permeation chromatography (GPC), FTIR, 1H NMR spectroscopy, and thermogravimetric analysis (TGA). The resulted cationic flocculant may be...
Article Proceedings of 2012 IEEE Conference on Control, Systems and Industrial Informatics, ICCSII 2012 ; 2012 , Pages 151-154 ; 9781467310239 (ISBN) ; Darus, I. Z. M ; Taghavi, A. H ; IEEE Indonesia Section ; Sharif University of Technology
The front double wishbone suspension parameters are related as a multi-body model. By replacing the new suspension and steering hard points, the performance of the suspension system is studied using CATIA and MSC ADAMS software for modeling and analyzing, respectively. In this case two tests were done, steady state circular test in ADAMS/View and parallel wheel travel in ADAMS/Car. The strut position is directly related to Kingpin inclination angle and scrub radius. The increase the amount of these two parameters has an effect on steering performance in low speed and negative displacement, such as camber, caster and Kingpin inclination angles in negative displacement of wheels. Moreover, the...
An experimental study on the effect of ultrasonication on thermal conductivity of ferrofluid loaded with carbon nanotubes, Article Thermochimica Acta ; Volume 617 , October , 2015 , Pages 102-110 ; 00406031 (ISSN) ; Salimpour, M. R ; Saghafian, M ; Shafii, M. B ; Sharif University of Technology
Nanofluids containing Fe
3O 4 and carbon nanotubes nanoparticles emulsified and dispersed using gum arabic (GA) and tetramethylammonium hydroxide (TMAH) were made and characterized for potential use as heat transfer fluids. Due to the interaction between the TMAH and GA molecules, the magnetic nanoparticles and CNTs were physically adsorbed. This paper reports an experimental work on the effect of ultrasonication on thermal conductivity of this aqueous suspension. The characterization and surface morphology of the dried samples were studied by using XRD and TEM measurements. Experiments were conducted in the magnetic nanoparticles mass concentration range 0.494-2.428%,...
The effect of nano-size additives on the electrical conductivity of matrix suspension and properties of self-flowing low-cement high alumina refractory castables, Article Ceramics International ; Volume 36, Issue 4 , 2010 , Pages 1411-1416 ; 02728842 (ISSN) ; Sagaeian, A ; Daghighi, A ; Nemati, Z. A ; Sharif University of Technology
Influence of two nano-size additives oSubject:A. Suspensions. Subject:C. Electrical conductivity. Subject:Castable. Subject:E. Refractories. Subject:Castables. Subject:Electrical conductivity. Subject:Electrical property. Subject:High alumina. Subject:matrix. Subject:Mechanical strength. Subject:Nano-size. Subject:Polycarboxylate ethers. Subject:Refractory castables. Subject:Working time. Subject:Alumina. Subject:Cement additives. Subject:Electric conductivity. Subject:Ethers. Subject:Suspensions (fluids) Subject:Refractory materials. n electrical properties of suspension matrix of self-flowing low-cement high alumina refractory castable is investigated. For this purpose, castament FS 10 and...
Experimental investigation of drag and lift forces on microparticles in low reynolds number poiseuille flow in microchannel, Article Journal of Dispersion Science and Technology ; Volume 37, Issue 12 , 2016 , Pages 1767-1777 ; 01932691 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Taylor and Francis Inc
In this paper, the hydrodynamic drag and lift forces on microparticles in a dilute suspension in low Reynolds number Poiseuille flow in a microchannel is experimentally investigated using microscopic image analysis. An effective technique is applied to manipulate single-particle tracking in order to determine the velocity field and hydrodynamic forces on microparticles with diameter-to-channel height ratio of 0.1 (Formula presented.) in microchannels. The results show that there is a distance near the walls of the channel in which the hydrodynamic coupling between the particles and channel walls is considerable. Also, the magnitude of drag force that is imposed on the particles with...
High flux electrospun nanofiberous membrane: Preparation by statistical approach, characterization, and microfiltration assessment, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 59 , 2016 , Pages 474-483 ; 18761070 (ISSN) ; Mousavi, S. A ; Bastani, D ; Sharif University of Technology
Taiwan Institute of Chemical Engineers
Preparation, characterization and evaluation of new generation of micro-filters based on polyacrylonitrile electrospun nanofiberous membrane (ENM) were thoroughly investigated. First, quantitative relationships between average diameter, bead area density of nano-fibers and certain electrospinning parameters, i.e., concentration, voltage, spinning distance, and feed rate, were established by empirical modeling based on a central composite design. The analysis revealed that concentration, voltage and distance are the significant parameters. Also, adequacy checking indicated the appropriateness of fit for the models. Afterwards, bead-free ENMs with diameter of 100-500 nm were prepared and...
Rolled graphene oxide foams as three-dimensional scaffolds for growth of neural fibers using electrical stimulation of stem cells, Article Carbon ; Volume 97 , 2016 , Pages 71-77 ; 00086223 (ISSN) ; Ghaderi, E ; Shirazian, S. A ; Rahighi, R ; Sharif University of Technology
Graphene oxide foam (GOF) layers with thicknesses of ∼15-50 μm and density of ∼10 graphene oxide (GO) sheets/μm were fabricated by precipitation of chemically exfoliated GO sheets in an aqueous suspension at ∼80 °C under UV irradiation. Then, rolled GOFs with desirable scales were developed as electrically conductive 3D-scaffolds and applied in directional growth of neural fibers, through differentiation of human neural stem cells (hNSCs) into neurons under an electrical stimulation. X-ray photoelectron spectroscopy indicated that the UV irradiation resulted in partial deoxygenation of the layers. Scanning electron microscopy and Raman spectroscopy confirmed the presence of multilayer GO...
Stabilization of the suspension of zirconia microparticle using the nanoparticle halos mechanism: zeta potential effect, Article Journal of Dispersion Science and Technology ; Volume 37, Issue 1 , 2016 , Pages 6-13 ; 01932691 (ISSN) ; Saidi, M.H ; Zabetian, M ; Sharif University of Technology
Taylor and Francis Inc 2016
An experimental study has been conducted to investigate the effect of silica nanoparticle halos on the stability of the zirconia aqueous suspension. The results of turbidity measurements showed that addition of nanoparticles to the suspension increases the stability of the zirconia suspension for all pH values. The achieved stability refers to the formation of nanoparticle halos around the microparticles that can be observed by scanning electron microscopy (SEM) imaging. The best stabilization is achievable when zirconia microparticles are at the isoelectric point. The minimum stabilization occurs when microparticles have relatively high zeta potential and the force between micro and...