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Journal ArticleDOI

Unsteady flow of a dusty conducting fluid through a pipe

Ali J. Chamkha1
01 May 1994-Mechanics Research Communications (Pergamon)-Vol. 21, Iss: 3, pp 281-288
TL;DR: In this article, the influence of the magnetic field on the flow properties in situations where the particle phase is considered dense enough to include the particulate viscous stresses was investigated. But the authors focused on the effect of the presence of solid particles on the performance of such devices.
About: This article is published in Mechanics Research Communications.The article was published on 1994-05-01. It has received 34 citations till now. The article focuses on the topics: Plug flow.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors scrutinize the chemically reactive flow of second-grade nanoliquid between two infinite plates, and the impact of sundry parameters on flow, temperature and concentration fields is studied with the help of graphic illustrations.
Abstract: The main theme of this communication is to scrutinize the chemically reactive flow of second-grade nanoliquid between two infinite plates. The MHD fluid is considered. Both plates approach symmetrically to each other, generating squeezing flow. The Buongiorno model is utilized for the modeling. Viscous dissipation and Ohmic heating effects are further considered. The total irreversibility rate is achieved via thermodynamics second law. To transform the reactants into products, a concept of activation energy is used. The nonlinear PDEs are altered into ordinary ones through similarity transformations and solved through homotopy analysis method. The impact of sundry parameters on flow, temperature and concentration fields is studied with the help of graphic illustrations. Velocity and temperature gradients are discussed numerically through Tables 2 and 3. The velocity of fluid particles increases versus squeezing parameter, while temperature field decreases. The entropy rate and Bejan number demonstrate the contrast influence against Brinkman number.

107 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the utilization of nanofluids with distinct plate heat exchanger (PHE) geometries, and concluded that the operating temperature of nanoparticles plays a key role in the effectiveness of the PHE and heat transfer enhancement.
Abstract: The application of nanofluids has dramatically increased from the past two decades. Nanofluids have elegantly captivated the attention of researchers nowadays. At present, various papers are being reported dealing with this interesting domain, allied with fascinating applications. However, the nanofluids being captives these days depicts the crucial need to bestow the comprehensive review of nanofluids application in distinct domains. This paper examines the utilization of nanofluids with distinct Plate Heat Exchanger (PHE) geometries. All the reported studies are alienated to two main categories; experimental and numerical. Furthermore, critical information regarding nanoparticle size, base fluids, analytical methods, heat transfer enhancement, flow regime, and pressure drop is presented in a comprehensive table in each section. Also, it was ultimately found that all the studies; analytical, experimental and numerical gave desired and appreciable thermal performance compared to conventional fluids. Author also reported the statistical analysis for the past published papers and the results show the increasing importance of nanofluids application in plate heat exchanger. Most of the studies showed preferred thermal behaviour, heat transfer enhancement, reduction in entropy generation and reduction in exergy destruction compared to the base fluids. An increase in Reynolds number can provide better heat transfer rates. The operating temperature of nanofluids plays a key role in the effectiveness of heat exchanger and heat transfer enhancement. Almost all the studies have demonstrated the preferred nanofluids thermal behaviour in plate heat exchanger, compared to the base fluid but Chevron and Corrugated type geometry of plate heat exchanger gives the appreciable enhancement in Nusselt number.

82 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigate the heat transfer of laminar and turbulent pulsating Al2O3/water nanofluid flow in a two-dimensional channel and propose a numerical analysis of heat transfer.
Abstract: The purpose of this paper is to investigate the heat transfer of laminar and turbulent pulsating Al203/water nanofluid flow in a two-dimensional channel. In the laminar flow range, with increasing Reynolds number (Re), the velocity gradient is increased. Also, the Nusselt number (Nu) is increased, which causes increase in the overall heat transfer rate. Additionally, in the change of flow regime from laminar to turbulent, average thermal flux and pulsation range are increased. Also, the effect of different percentage of Al2O3/water nanofluid is investigated. The results show that the addition of nanofluids improve thermal performance in channel, but the using of nanofluid causes a pressure drop in the channel.,The pulsatile flow and heat transfer in a two-dimensional channel were investigated.,The numerical results show that the Al2O3/Water nanofluid has a significant effect on the thermal properties of the different flows (laminar and turbulent) and the average thermal flux and pulsation ranges are increased in the change of flow regime from laminar to turbulent. Also, the addition of nanofluid improves thermal performance in channels.,The originality of this work lies in proposing a numerical analysis of heat transfer of pulsating Al2O3/Water nanofluid flow -with different percentages- in the two-dimensional channel while the flow regime change from laminar to turbulent.

45 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive theoretical and numerical investigation is presented for two fluids with different physical properties, including buoyancy and viscous heating, where numerical solutions for reduced non-dimensional Navier-Stokes equations and coupled energy conservation equation are obtained using a finite difference method with second-order accuracy.

20 citations

Journal ArticleDOI
TL;DR: In this article, the authors considered a three-layered liquid model in which the core and peripheral regions of the tube are occupied by micropolar and Newtonian fluids, respectively, and a thin glycocalyx layer near the wall is considered that represents the porous region due to the deposition of carbohydrates, fibrous tissues or macromolecules inside the interior surface of tube wall.
Abstract: The transport theory of three-layered fluid flow and heat transfer aspects in porous layered tubes is considered in the present work to study the flow of microlevel fluids through porous layered microvessels. The transportation of energy through porous media and the applications associated with heat transfer in physiological aspects are analyzed. Blood is considered as three-layered liquid model in which the core and peripheral regions of the tube are occupied by micropolar and Newtonian fluids, respectively. A thin glycocalyx layer near the wall is considered that represents the porous region due to the deposition of carbohydrates, fibrous tissues or macromolecules inside the interior surface of the tube wall. Analytical expressions for the various flow quantities like velocity, temperature profile, flow rate, flow impedance and additional quantities like hematocrit and Fahraeus effect are obtained and the impacts of various parameters like heat transfer and porous layer parameters are analyzed pictorially for two different formulations (no-spin and no-couple stress conditions). A noteworthy observation is that the impact of no-couple stress condition is relatively more significant in flow quantities, hematocrit and Fahraeus effect than the no-spin condition at the interface. The motivational work of the blood flow through porous blood vessels by selecting the micropolar fluid for the microlevel effects of the molecules may leave a significant impact in the treatment of the various diseases in medical sciences.

16 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a review dealing with a certain restricted portion of the mechanics of heterogeneous media is presented, where the problem of detailed transport processes between particles and gas may be treated independently of the complete dynamical problem, and this aspect, being a study of its own, will be suppressed to a considerable extent.
Abstract: This review deals with a certain restricted portion of the mechanics of heterogeneous media. The volume fraction of the solid-particle or droplet cloud is considered to be so small that the interaction between individual particles may be neglected or highly simplified. This limitation applies to the individual flow fields about the particles as well as to collisions, and to heat and mass transfer as well as to momentum exchange between phases. Under this circumstance, the problem of detailed transport processes between particles and gas may be treated independently of the complete dynamical problem, and this aspect, being a study of its own, will be suppressed to a considerable extent here. There are problems, such as the impact of particles on walls, the concentration separation in boundary layers or pipe flow, in which the distortion of the particle flow field due to a solid wall or another particle is the central physical issue. These problems therefore lie outside the scope of the review. On the other hand, the structure of shock waves, sound attenuation, and many flow-field problems can be treated within our present restrictions. The basic equations and exchange processes will be introduced first, together with the physical parameters that indicate the relative importance of the particle cloud and the limitations of the dusty-gas concept. Then several different problems will be discussed that lead to some of the significant results in the field and illustrate analytical techniques that have proven useful.

652 citations

Journal ArticleDOI
TL;DR: In this article, a theory for the fully-developed flow of gas and particles in a vertical pipe is presented, and the relation between gas pressure gradient and the flow rates of the two phases is predicted, over the whole range of cocurrent and countercurrent flows, together with velocity profiles for both phases and the radial concentration profile for the particles.
Abstract: A theory is presented for the fully-developed flow of gas and particles in a vertical pipe. The relation between gas pressure gradient and the flow rates of the two phases is predicted, over the whole range of cocurrent and countercurrent flows, together with velocity profiles for both phases and the radial concentration profile for the particles. The gas and the particles interact through a drag force depending on their relative velocity, and there are mutual interactions between pairs of particles through inelastic collisions. This model is shown to account for marked segregation of gas and particles in the radial direction, and the predicted relation between the pressure gradient and the flow rates of the two phases is surprisingly complex.

613 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured important flow quantities such as local void fraction, liquid velocity and the Reynolds stresses using both single-sensor and three-Sensor hot-film anemometer probes, and found that the observed wall peaking and coring phenomena in up and down flows could be predicted by considering the turbulence structure of the continuous phase and lateral lift force acting on the dispersed phase.

399 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the induced potential difference between two electrodes on the walls of a circular pipe with laminar flow and showed that if the walls are conducting but without contact resistance, the potential difference is 0·926 of the value corresponding to the case of uniform velocity.
Abstract: The flow rate of liquid metals is commonly measured by electromagnetic flowmeters. In these the fluid moves through a region of transverse magnetic field, inducing a potential difference between two electrodes on the walls of the pipe. The ratio of signal to flow rate is dependent on the velocity profile, and this is affected by electromagnetic forces.In this paper the ultimate steady velocity profile and its associated pressure gradient and induced potential are calculated for the case of laminar flow in a circular pipe whose walls are conducting but without contact resistance. Laminar flow is encouraged by a transverse field. When the fluid conductivity and field strength are sufficiently high, boundary layers occur with a thickness inversely proportional to normal field intensity. The induced potential difference is then 0·926 of the value corresponding to the case of uniform velocity if the walls are non-conducting.The distance the fluid must travel after entering the transverse field before the steady state is reached is next estimated by a Rayleigh approximation. The inlet velocity is taken to be uniform and effects which occur at the edge of the field are neglected. The process falls into two stages, first a boundary-layer growth and then an adjustment of the velocity away from the walls, occupying a much greater length of pipe. The entry length is shorter than it is in the case of flow in a rectangular pipe, but is still too long for appreciable distortion of the velocity profile to occur within practical flowmeters except at low flow rates. The pressure drop associated with the adjustment of the velocity profile is found to be independent of field strength, if this is high, and about one-eighth of the drop which occurs in the non-conducting case.Experiments are described in which steady-state pressure gradients and induced potential differences were measured in mercury flowing along Perspex pipes of 0·5 and 0·25 in. bore in transverse fields up to 14500 gauss. The results confirmed the steady-state theory within the limitations of experimental accuracy and the assumption in the theory of high conductivity and an intense field. The experiments also covered the entry region in many cases, and showed that the theoretical entry lengths were correct in order of magnitude but over-estimated. However, the exact entry condition was uncertain, and steady readings were difficult to obtain in the entry region.

198 citations

Journal ArticleDOI
TL;DR: In this paper, a solution to the problem of the steady one-dimensional flow of an incompressible, viscous, electrically conducting fluid through a circular pipe in the presence of an applied (transverse) uniform magnetic field was obtained.
Abstract: The solution is obtained to the problem of the steady one-dimensional flow of an incompressible, viscous, electrically conducting fluid through a circular pipe in the presence of an applied (transverse) uniform magnetic field. A no-slip condition on the velocity is assumed at the non-conducting wall. The solution is exact and thus valid for all values of the Hartmann number. Excellent agreement exists between the present theoretical results and the experimental values obtained by Hartmann & Lazarus (1937) in the low to medium Hartmann number range. The high Hartmann number case is treated by Shercliff (1962) in the following paper.

182 citations