Top PDF On the transport properties of fluid-particle flow

On the transport properties of fluid-particle flow

On the transport properties of fluid-particle flow

Drag Formula for a Clas s of Axially Symmetric Particles in a Uniform Flow 10 Viscous Interaction Between a Small Number of Spherical Particle s 26 The Effect of Continuous Solid Boundar[r]

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A GPU-based coupled SPH-DEM method for particle-fluid flow with free surfaces

A GPU-based coupled SPH-DEM method for particle-fluid flow with free surfaces

Particle-fluid flows with free-surfaces are commonly encountered in many industrial processes, such as wet ball milling, slurry transport and mixing. Accurate prediction of particle behaviors in these systems is critical to estab- lish fundamental understandings of the processes, however the presence of the free-surface makes modelling them a challenge for most traditional, continuum, multi-phase methodologies. Coupling of smoothed particle hy- drodynamics and discrete element method (SPH-DEM) has the potential to be an effective numerical method to achieve this goal. However, practical application of this method remains challenging due to high computational demands. In this work, a general purposed SPH-DEM model that runs entirely on a Graphic Processing Unit (GPU) is developed to accelerate the simulation. Fluid-solid coupling is based on local averaging techniques and, to accelerate neighbor searching, a dual-grid searching approach is adapted to a GPU architecture to tackle the size difference in the searching area between SPH and DEM. Simulation results compare well with experimental results on dam-breaking of a free-surface fl ow and particle- fl uid fl ow both qualitatively and quantitatively, confirming the validity of the developed model. More than 10 million fluid particles can be simulated on a single GPU using double-precision floating point operations. A linear scalability of calculation time with the number of particles is obtained for both single-phase and two-phase fl ows. Practical application of the developed model is demonstrated by simulations of an agitated tubular reactor and a rotating drum, showing its capability in han- dling complex engineering problems involving both free-surfaces and particle-fluid interactions.
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Pressure dependence of fluid transport properties of shallow fault systems in the Nankai subduction zone

Pressure dependence of fluid transport properties of shallow fault systems in the Nankai subduction zone

Permeability decreased with effective pressure as a power law function. Permeability values in the fault zones were 8 × 10 −18 m 2 at site C0004 and 9 × 10 −18 m 2 at site C0007. Stratigraphic variation in transport properties suggests that the megasplay fault zone may act as a barrier to fluid flow, but the frontal thrust fault zone might not. Depth variation in permeability at site C0007 is probably controlled by the mechanical compaction of sediment. Hydraulic diffusivity at shallow depths was approximately 1 × 10 −6 m 2 s −1 in both fault zones, which is small enough to lead to pore pressure generation that can cause dynamic fault weakening. However, absence of a very low permeable zone, which may have formed in the Japan Trench subduction zone, might prevent facilitation of huge shallow slips during Nankai subduction zone earthquakes. Porosity tests under dry conditions might have overestimated the porosity.
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Improvement of Calculation Stability for Slow Fluid Flow Analysis Using Particle Method

Improvement of Calculation Stability for Slow Fluid Flow Analysis Using Particle Method

The height of the casting was 180 mm, and the upper half of the casting was 25 mm and the lower half was 40 mm in di- ameter, respectively. The physical properties used in the cal- culation are shown in the Table 1, and the fluid was poured from the upper side with a rate of 100 g/s and pouring finish within 4 s. The results are shown in the Fig. 8. Figure 8(a) is the result of MR1-1.0 at 4.5 s, showing unnatural pressure distribution at the bottom of the casting, and hopping of the casting particles. At the last moment, the fluid flow was very slow. However the pressure in the casting was unnaturally high under the shoulder. In such shapes with shoulders, posi- tional correction in the correction phase tends to be insuffi- cient, and the pressure under the shoulder will be accumulat- ed unnaturally. As a result, unnatural hopping occurs, and the calculation will result in failure. In the Fig. 8(b), we can find that the proposed method improves the calculation stability. The calculated pressure value at the bottom agreed well with the theoretical value, 4410 Pa. It is possible to improve calcu- lation stability by using smaller Δt. However the pressure or velocity oscillation problem will remain, and also, longer cal- culation time will be required because of higher maximum velocity.
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CHEMICALLY REACTIVE VISCOELASTIC FLUID FLOW IN PRESENCE OF NANO PARTICLE THROUGH POROUS STRETCHING SHEET

CHEMICALLY REACTIVE VISCOELASTIC FLUID FLOW IN PRESENCE OF NANO PARTICLE THROUGH POROUS STRETCHING SHEET

performance is still going due to effective applications in the field of cooling (transformer cooling, electronics device cooling, silicon mirror cooling, vehicles cooling, controlling fusion), biomedical (magnetic cell separation, drug delivery, cancer therapeutics, cryopreservation, nano cryosurgery) etc. The term “nano fluid” can be refers to a class of fluids by suspending nanometre sized (1-100 nm diameters) particles in common base fluids of highly enhanced thermal properties (Ferdows et al., 2013; Dogonchi et al., 2016). This type of fluids has highly industrial importance because of its unique chemical and physical properties. It has a higher thermal conductivity which controlled significant enhancement due to the rate of heat transfer.
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Computational Fluid Dynamics Simulation of a Crude Oil Transport Pipeline: Effect of Crude Oil Properties

Computational Fluid Dynamics Simulation of a Crude Oil Transport Pipeline: Effect of Crude Oil Properties

To study the effect of crude oil properties on the transport profile inside a pipeline, numerical simulation was tested under laminar unsteady state conditions. The Reynolds number of the flow in the pipeline was in the range of 35.63 to 261.16, depending on the condition. It is apparent that the Reynolds number is low for crude oil flow due to its high viscosity. The Peclet numbers were in the range of 15,999.00 to 22,752.29, and the Biot number was 1.83. Because the Peclet number was high, the convection was important. In addition, in this study, the Biot number implies that the conduction was much slower than the convection and temperature gradients dominant in the pipeline. A crude oil liquid flow was simulated with a 30,000 cell straight pipe model after grid independency testing. The simulation test operated until a steady state was reached. The details about the validation of this study used to develop the computer program code with literature experimental data can be found in Rukthong [15] and Rukthong et al. [16]. In this study, the result trends from the developed computational fluid dynamics simulation program were verified with the commercial program, ANSYS FLUENT [17], and theoretical transport phenomena concept.
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Flow And Heat Transfer Over A Stretching Sheet Embedded In A Porous Media With Fluid-Particle Suspension

Flow And Heat Transfer Over A Stretching Sheet Embedded In A Porous Media With Fluid-Particle Suspension

A mathematical model is presented for analyzing the boundary layer flow and heat transfer of dusty fluid over a stretching sheet embedded in a porous medium. Temperature dependent fluid properties are assumed to vary as a function of the temperature. Using a similarity transformation, the governing coupled non-linear partial differential equations are transformed into a system of coupled non-linear ordinary differential equations and solved numerically by the Keller-box method. The numerical solutions are compared with the approximate analytical solutions, obtained by a perturbation technique. The analysis reveals that even in the presence of variable fluid properties the transverse velocity of the fluid is to decrease with an increase in the fluid-particle interaction parameter. This observation holds even for porous medium. Furthermore, the effects of the physical parameters on the fluid velocity, the velocity of the dust particle, the density of the dust particle, the fluid temperature, the dust-phase temperature, the skin friction, and the wall-temperature gradient are assessed through tables and graphs.
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Forcheimeir Effect on Transport Process with Internal Heat Source and Varying the Fluid Properties

Forcheimeir Effect on Transport Process with Internal Heat Source and Varying the Fluid Properties

The Analysis of Internal Heat source for transport processes of the physical system formulated with Forcheimeir model is studied. The extended Darcy model is used here. For Physical problem considered here, the governing measures are highly coupled. To solve them, initially similarity transformations are used to convert them into ODE and solved approximately. RK method of fifth order followed by Newton-Raphson method is employed. The graphical representations are obtained for transport processes, where the features of fluid flow are discussed. The exponential form of internal heat source enhances melting and impedes freezing. The significance of inertial parameter is highly influenced in decreasing the flow field. Besides, skin friction, heat and mass transport graphical interpretations are made for different physical parameters. A good agreement is found when interpretation of the effects of various significant parameters are analysed and the results are compared.
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Computational analysis of non-spherical particle transport and deposition in shear flow with application to lung aerosol dynamics: A review

Computational analysis of non-spherical particle transport and deposition in shear flow with application to lung aerosol dynamics: A review

(ii) Distributed Lagrangian Multiplier Method. The distrib- uted Lagrange multiplier (DLM) method is based on the fictitious–domain method. The fictitious domain is derived from the idea that fluid fills the space inside of the particles as well as outside. Since fluid fills the whole flow domain, including particle volumes, a simple fixed finite element mesh can be generated to solve for the velocities of the fluid and the particles. As the mesh does not need to be refreshed in every time step, it is much more efficient when compared to the ALE method. The particle is tracked by using boundary control points that are on the particle boundary and move with the particle. The grid (see Fig. 4) does not conform to the shape of the particle. The nodes that are inside the particle boundary have their calculated velocity, i.e., the velocity which at that point in the particle would have due to a rigid body motion. Since fluid occupies the region of the particle, the Navier–Stokes equations must be solved to obtain velocity values for any point inside or on the surface of the particle. The body force term in the Navier–Stokes equations is multiplied by a constant corresponding to that particular position that will yield a velocity due to rigid body motion.
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Flow structures and fluid transport for the hydromedusae Sarsia
tubulosa and Aequorea victoria

Flow structures and fluid transport for the hydromedusae Sarsia tubulosa and Aequorea victoria

In the present study, we present the Lagrangian coherent structures (LCS) seen in the results of numerical simulations of hydromedusae swimming as well as several examples of particle motion in the resulting flow. The hydromedusae examined are Aequorea victoria Murbach and Shearer 1902, a paddling or rowing type of hydromedusa, and Sarsia tubulosa M. Sars 1835, a jetting type of hydromedusa. We believe this to be the first numerical study of this type. The actual motion of the hydromedusa, reproduced from digitized videos of the swimming hydromedusae, is used to compute the surrounding velocity field. A brief description of the numerical method for computing the velocity field is included in Materials and methods. The use of computational fluid dynamics (CFD) data instead of an empirical velocity field from digital particle image velocimetry (DPIV), or similar, results in higher resolution of the LCS as well as greater accuracy in subsequent calculations. Additionally, there are significant difficulties in obtaining high-quality results from DPIV for swimming hydromedusae. DPIV results are only available for the time during which the hydromedusa is properly oriented within the field of view, perhaps only a few swimming cycles depending on many factors. Additionally, the resolution obtained from DPIV depends on the concentration of particles in a given region. In general, the distribution of particles may be highly non-uniform. The particles will be drawn toward certain flow structures, just as dye is drawn into vortices in dye visualization experiments, but other areas of the flow may be left with few particles. None of these difficulties are present in our method. It is only necessary to capture a good swimming cycle. The periodic swimming motion may then be determined up to the resolution of the camera used and iterated for as many swimming cycles as desired.
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Heat transfer, fluid transport and mechanical properties of porous copper manufactured by lost carbonate sintering

Heat transfer, fluid transport and mechanical properties of porous copper manufactured by lost carbonate sintering

become greater at higher flow velocities, resulting in larger pressure gradient through the porous media (Antohe & Lage 1997). The mechanism responsible for this turbulence is the drag force imposed on a fluid by the pore walls which impede the flow (Carman, 1956). In steady viscous or streamline flow, the resistance arises solely from viscosity. As the velocity increases, the regular pattern of streamline flow becomes unstable, and gives way to a regime where large number of small, randomly distributed local eddies form spontaneously. This results in the dissipation of the kinetic energy of fluid motion as heat and hence increases the resistance to flow. This resistance can be described as inertial resistance and depends on the kinetic energy per unit volume of the fluid, i.e. on ρ f v 2 . Therefore, in general engineering applications, the law governing this fluid flow is a modified version of Darcy’s equation, with inertial resistance superimposed on the viscous resistance (Dupuit 1863; Forchheimer 1901):
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Particle transport in a pulmonary flow

Particle transport in a pulmonary flow

Pulmonary flow is characterized by a series of bifurcations. The laminar flows in this type of bifurcations have been studied by many authors, but few researchers have focused on the efforts of the upstream turbulence. Indeed, although the flow is laminar in the bronchi (at least for normal respiration), it is turbulent in the upper airways. This turbulent appearance is paramount, as this significantly alters the transport and deposition of particles. In addition, many current research considers a steady flow at the entrance and therefore do not reproduce the cycle of breathing. These modeled air flows through an anatomically realistic system conduits and branches, are governed by contraction and expansion movements of the pulmonary system and alveolar sacs. Today, fluid dynamics (a science of everyday, but that seems very unknown) is a very active area of research with many unsolved or partially solved problems yet. She always uses numerical methods better known under the name of Computational Fluid Dynamics (CFD). In order to understand and characterize the transport of inhaled particles in human airways, many authors conducted various experimental and numerical studies that led to relevant results. We will be interested in this study to provide a reliable and comprehensive numerical modeling of particle transport in pulmonary flow without taking into account the movements imposed by breathing with the help of CFD-ACE commercial calculation code.
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Some Features of Flow and Particle Transport in Porous Structures

Some Features of Flow and Particle Transport in Porous Structures

Porous filters have been used for removing particles with success for many years [4]. Their wide application in air pollution control and in different technologies is due to their reliability in the separation of particles and relatively low operating cost. One of the most important issues in filtration is to know how media’s physical properties varied during operating conditions. Filter’s collectors (microscopic scale) are properly designed if, during a reasonably long filtering operation, filter’s collection efficiency is high and media’s flow resistance is below assumed value [5-6]. Description of flow field
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MHD Peristaltic Transport of Couple Stress Fluid in an Inclined Channel with Hall Current and Slip Flow

MHD Peristaltic Transport of Couple Stress Fluid in an Inclined Channel with Hall Current and Slip Flow

current effect in oscillatory flow of a couple stress fluid in an inclined channel. Eldabe et al. [1] studied the effects of heat and mass transfer on the MHD flow of an incompressible, electrically conducting couple stress fluid through a porous medium in an asymmetric flexible channel over which a traveling wave of contraction and expansion is produced, resulting in a peristaltic motion. Sankad and Radhakrishnamacharya[12] contributed towards the effect of magnetic field on the peristaltic transport of couple stress fluid in a channel with different wall properties. Shit and Roy[14] discussed the effect of slip velocity on peristaltic transport of a physiological fluid through a porous non-uniform channel under the long wave length and low-Reynolds number assumptions. Kothandapani and Srinivas [7] analysed the effect of elasticity of the flexible walls on the MHD peristaltic flow of a Newtonian fluid in a two-dimensional porous channel with heat transfer under the assumptions of long wavelength and low- Reynolds number.
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Rotational flow in fluid dynamics

Rotational flow in fluid dynamics

equation (4)# that K muet be 0oro and equation (2) le thuo an Identity. On the other hand# If K la aeeumed to be aero# it can be easily shown that the fluid met be bara tropic# Thus# the govei'nlng eqmtlono reduce to three in number# ao expected# namely equatlono (1)# (3) and (9). The temperature at any point can be obtained Imaediately from equation (4)# It should be noted that equation (9) la tho law governing loezi^yropio floi)# which le not the case in the rotational flow behliKa a bow shock wave# where the entropy 8# varleo from stream line to otreom lino# although tho otagnatlon enthal]%f for
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On a Couette Flow of Conducting Fluid

On a Couette Flow of Conducting Fluid

The governing equations presented in the previous section are highly nonlinear and exhibited no analytical solutions due to thermal radiation effect. In general analytical solution are very useful in validating computer routines of complicated time dependent two or three-dimensional free convective and radiating conducting fluid and comparison with experimental data. It is therefore of interest to reduce the governing equations of the present problem to the form that can be solved analytically. A special case of the present problem that exhibit analytical solution is the problem of steady state MHD natural convection Couette flow trapped between two infinite vertical plates in the presence of thermal radiation effects. The resulting steady state equations and boundary
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CFD-Calculation of Fluid Flow in a

CFD-Calculation of Fluid Flow in a

Analytical solutions to the Navier-Stokes equations are impossible to obtain for any systems but the simplest flows under ideal conditions. For real flows, a numerical approach must be adopted whereby a discretization method involves replacing the Navier- Stokes equations by their algebraic approximations, which can then be solved using a numerical method. The CFD approach uses Navier-Stokes equations and energy balances over control volumes, small volumes within the geometry at a defined location representing the reactor internals. The size and number of control volumes (mesh density) is user determined and will influence the accuracy of the solutions to a degree. After boundary conditions have been introduced in the system the flow and energy balances are solved numerically. An iteration process decreases the error in the solution until a satisfactory result has been reached. By using CFD in the simulation of coolant of the nuclear reactors a detailed description of the flow behavior within the barrel can be established, which can then be used in more accurate modeling.
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The CMS Particle Flow Algorithm

The CMS Particle Flow Algorithm

The Particle Flow (PF) algorithm [1] is based on a concept of global event reconstruction as it performs a correlation of the basic elements (i.e. tracks and clusters) obtained from all subdetector systems, in order to identify all particles in the event and measure their properties. An example is shown in Fig. 1 and Fig. 2 where a jet with transverse momentum of 65 GeV, simulated in the CMS detector [2], is made of only five particles: two charged hadrons (a π + and a π − ), two photons (from the decay of a π 0 ) and one neutral hadron (a K 0

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Simulation of Particle Agglomeration in Turbulent Flow

Simulation of Particle Agglomeration in Turbulent Flow

The fine particles in air are mainly from the combustion of fossil fuels. They are difficult to be removed completely by conventional dust collector because of the small size [3]. Particle agglomeration technology is a potential method to improve the removal efficiency of fine particles using the conventional dust col- lector. Several external fields and some chemical agents were applied to make fine particles to “grow” into large particles agglomeration which can be filtered easily. The agglomeration methods mainly include acoustic agglomeration, How to cite this paper: Yan, P.L., Sun,
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Determination of mist flow characteristic for MQL technique using particle image velocimetry (PIV) and computer fluid dynamics (CFD)

Determination of mist flow characteristic for MQL technique using particle image velocimetry (PIV) and computer fluid dynamics (CFD)

no one was able to prove that the statement is true or no one have ever suggested a systematic procedure to prove MQL’s efficiency. The effectiveness and the working principle of MQL are still questionable with very few explanations provided. The aim of this study is to determine the desirable flow pattern of the mist flow in order to choose the nozzle distance from the cutting tool for the minimum quantity lubricant in machining process using Particle Image Velocimetry (PIV) and Computer Fluid Dynamics (CFD).

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