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Coiled tubing (CT) drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources. However, the development of CT drilling technology is restricted by cuttings accumulation in the wellbore due to non-rotation of the drill string and limited circulating capacity. Cuttings cleaning becomes more difficult with the wall resistance of pipe-wellbore annulus on the cutting transport. Accurate description of particle transport process in the pipe-wellbore annulus is, therefore, important for improving the wellbore cleanliness. In this study, high-speed camera is used to record and analyze the settling process of particles in the transparent annulus filled with power-law fluids. A total of 540 tests were carried out, involving dimensionless diameters of 0.10–0.95 and particle Reynolds Numbers of 0.01–12.97, revealing the effect of the dimensionless diameter and particle Reynolds number on the annulus wall effect, and the wall factor model with an average relative error of 2.75% was established. In addition, a dimensionless parameter, Archimedes number, independent of the settling velocity, was introduced to establish an explicit model of the settling velocity of spherical particles in the vertical annulus, with the average relative error of 7.89%. Finally, a calculation example was provided to show how to use the explicit model of settling velocity in annulus. The results of this study are expected to provide guidance for field engineers to improve the wellbore cleanliness of coiled tubing drilling.

Empirical correlations and experimental works relating the drag coefficient (CD) of spheres to the Reynolds number (Re) and Re to the Archimedes number (Ar) were reviewed with a focus on the correlations applicable to the entire Re range. In addition, experiments with various spherical particles and fluids for the entire range of Re were conducted using high-speed video and added to the literature data. One of the correlations from the literature for Re-Ar and a modified correlation for CD–Re were found to best fit the experimental results. The analysis also established new correlations for Re–Ha (a non-dimensional number for velocity not including particle size) and CD–Ar. The latter is easier to use than the common CD–Re curve.

The angle of repose, angle of tilting, and Hausner ratio are frequently used to estimate the flowability of a particulate material. In this study, these factors were determined for 12 samples as a function of the moisture content. The measurements were thoroughly analyzed and indicate that the angle of tilting is the most appropriate for describing a material's response to moisture content. The flowability results clearly showed three types of materials according to their response to moisture content: solid particles, porous particles, and size-changing particles. A thorough analysis of various sizes of spherical solid particles enabled the identification of five zones from dry to fully immersed in water, and a zone map could be obtained. In addition, a model predicting flowability as a function of moisture content and Archimedes number could then be developed. Further experiments are required to relate the zone map and model to other types of materials.

The hindrance of boundary to particle transport exists widely in various industrial applications. In this study, the wall drag force of parallel plates on settling particles was revealed through settling experiment. High-speed camera was used to record and analyze the settling process of particles in parallel plates that are filled with Newtonian fluids. A total of 600 experiments were carried out, involving the range of relative diameter and particle Reynolds number of 0.01–0.95 and 0.004–14.30, respectively. The wall drag coefficient was defined to quantitatively analyze the wall drag force of the parallel plates. The influence of relative diameter, particle properties, rheological properties, and the settling dynamic process on the wall drag coefficient was revealed, and the wall drag coefficient model with mean relative error of 5.90% was established. Furthermore, an explicit settling velocity model with mean relative error of 8.96% for the particle in parallel plates was developed by introducing a dimensionless variable independent of settling velocity, the Archimedes number. Finally, a calculation example was provided to clarify the using process of the explicit model. This research is expected to provide guidance for optimizing water hydraulic fracturing in the oil and gas industry.

In the current study, the settling, interaction, drafting, kissing, and tumbling of two identical and non-identical circular particles were simulated in a two-dimensional box in shear-thinning, Newtonian, and shear-thickening fluids by using the combined lattice Boltzmann-smoothed profile methods. Furthermore, the drag coefficient of one particle settling for different power-law indexes and Archimedes numbers was calculated. Also, the effect of the diameter ratio of the two particle pairs was considered during settling. The developed method was validated by simulating the settling of one particle and two identical particles in a Newtonian fluid. To consider two non-identical particles, two cases were examined. In Case A, the larger particle was above the smaller one and in the Case B, the smaller particle was above the larger one. The results showed that the two non-identical particles were separated more easily than the identical ones. In the settling of two particles under the same Archimedes number, the drafting and kissing time considerably increased by changing the non-Newtonian fluid behavior from a shear-thinning one to a shear-thickening one. Also, when the larger particle was above the smaller one, the time duration of the kissing stage increased with the decrease in the diameter ratio.

The modeling of the fluidization or sedimentation velocity of a suspension of solid particles is revisited by examining experiments conducted in either a liquid or a gas. A general expression is found in the case of negligible fluid inertia, i.e. at low Reynolds or Archimedes number. It is built as the product of the velocity of an isolated particle by three non-dimensional corrections that each takes into account a specific physical mechanism. The first correction reflects the variation of the buoyancy with the particle concentration. The second correction describes how the drag force increases with the concentration in case of negligible particle inertia. The third one accounts for the further increase of the drag when the particle inertia is increased. Remarkably, each correction only relies on a single of the three independent non-dimensional groups that control the problem: (1) the particle volume fraction Φs; (2) the ratio Φs/Φpack where Φpack is the bed packing concentration; (3) the Stokes number S t 0 , which characterizes the inertia of the particles and controls their agitation. Moreover, the onset of the instability that separates the homogeneous regime from the heterogeneous one is found to be controlled similarly by the Stokes number. Empirical expressions of the corrections are given, which provide a reliable tool to predict fluidization and sedimentation velocities for all values of the three non-dimensional numbers. The present results emphasize the crucial role of particle inertia, which is often disregarded in previous modeling approaches, such as that of Richardson and Zaki.

Cooling of electronic equipments is playing an important role in the last decades as a world experiences a technological boom in all fields. In this study, a numerical study for mixed convection cooling of microprocessor is investigated by the use of pure water and CuO-water nanofluid at six different volume concentrations. The model is built, meshed and simulated by Ansys Fluent Package 16.0 and a mesh independence test is carried out. The study is performed by changing heat load (115W, 130W), inlet velocity, at different concentrations of nanofluids (Pure water, 0.5%, 0.86%, 1.5%, 2.25%, 3.5%, 5%). The present results showed that using CuO-water nanofluids over pure water provides an enhancement in heat transfer characteristics. The dimensionless parameters such as Nusselt number, Archimedes number, Prandtl number, friction factor and dimensionless temperature are studied and correlated. An enhancement of 36.5% in thermal hydraulic performance is found at 0.50% volume fraction at Re = 1679.212. The data are correlated with maximum error of 4.1%.

The solid circulation rate is essential for design of pressurized circulating fluidized beds (PCFBs). With increasing pressure from atmospheric pressure to a few bars, the gas density linearly increases with the pressure, which affects the gas–solid flow characteristics. In this work, experiments were performed at room temperature in a cold PCFB apparatus with a riser of 3.3 m in height and 0.05 m in diameter. The solid circulation rate was studied from 20 to 80 kg/(m2·s) under various conditions with increasing pressure from 0.1 to 0.6 MPa and fluidizing gas velocity from around 1.5 to 8.0 m/s for different Geldart B group particles. Most of the conditions were in the flow regimes of core-annulus flow (CAF) only and CAF with a turbulent fluidized bed at the bottom. The trend of the apparent slip factor with the dimensionless slip velocity was similar at different pressures and for different average particle sizes, and it converged to an exponential function. An empirical equation was obtained by fitting the solid circulation rate with the operating parameters (particle transport velocity, particle volume fraction, Archimedes number, and Froude number), which is helpful for design and operation of PCFBs.

The angle of repose, angle of tilting, and Hausner ratio are frequently used to estimate the flowabilities of particulate materials. In this study, these parameters were measured for 65 samples. A visualization study showed that there are three mechanisms affecting the angle of repose. Only one is directly related to the flowability. Crucially, to eliminate the effect of wall friction, the measurement of the angle of repose should be conducted on a high-friction surface (such as one covered in glue) or within a ring. Further, although all three parameters can be described as a function of the Archimedes number, the performance of each material was different; thus, the results cannot be generalized. Only the Hausner ratio could be defined reasonably by a single function. A new flowability classification was developed for the three parameters, and the best metric to define flowability was found to be the Archimedes number.

This study analyzes the effect of moisture content and compression pressure on bed void fraction in different materials. The void fractions of several materials, both spherical and non-spherical, solid and porous, with different particle sizes and densities, were evaluated as functions of moisture content and compression pressure. In our previous study, the Archimedes number was found to be an appropriate parameter to describe particle behavior. In this study, the Archimedes number was found to be an appropriate non-dimensional number to describe the effects of moisture content and compression pressure. A general equation was developed to evaluate the effect of moisture content on liquid bridge forces in solid and porous particles. Furthermore, a general equation was developed based on the Heckel model to describe compressed particulate beds. Finally, we studied the compression of wet particles. The general equations presented in this study agree well with the experimental values.

This paper presents an analysis of all forces affecting the void fraction (VF) and density of a particulate bed. The bulk density of many materials, both spherical and non-spherical, with a variety of properties, including particle size and density, were measured in air and various liquids. The Archimedes number (Ar) was found to be an appropriate representation of the particle behavior that considered the van der Waals forces. The effects of buoyancy and viscous forces, as components of Ar, on the VF were shown by experiments in various liquids. Additional forces, such as friction, impact, and tapping were discussed quantitatively and qualitatively. Furthermore, the effect of the particle shape on the VF was considered. Finally, general equations for VF and density were developed for practical use. The major effects of the moisture content and compression pressure on the VF will be discussed in a following paper.

Current investigation presents the heat and mass transfer analysis for steady flow Oldroyd-B fluid induced by isothermally and exothermally stretching disks. The novel features of Joule heating, chemical reaction and Ohmic dissipations are also utilized in the energy and concentration equations. A non-dimensional set of transformations are introduced to convert the coupled partial differential system into a system of ordinary differential equations. The analytical solution of formulated dimensionless equations is obtained by using homotopy analysis method. The solution convergence is ensured carefully. The physical exploration of various dimensionless parameters on pressure, velocity, temperature and concentration profiles is presented. It is observed that heat transfer at lower disk increases with increment of Deborah number, Archimedes number and distance parameter. The rate of mass transfer at both surfaces of disk is enhanced for larger values of activation energy parameter and Deborah number.

The difference between homogeneous and bubbling fluidization behaviors has been studied for the past 70 years, where several researchers have reported on the influence of interparticle forces in fluidization. Although interparticle forces such as van der Waals forces are evident in a real system, these forces are not the determinant in homogeneous fluidization, which can be simulated without any interparticle forces. In our previous study, the difference in fundamental mechanisms of the two fluidization states was analytically determined with a dimensionless gravity term, comprising the Reynolds number, Archimedes number, and density ratio. Nevertheless, some researchers insist that interparticle forces are dominant and a hydrodynamic force is not dominant. In this study, a dimensional analysis was applied to obtain a dominant parameter for distinguishing two fluidizations. Furthermore, some parameters were examined by comparing the experimental data in previous studies. The results indicated that hydrodynamic force is the dominant factor and the dimensionless gravity term is the dominant parameter in differentiating the two fluidized states.

The supercritical-water fluidized bed (SCWFB) is a reactor for coal and biomass gasification without pollutant emission. We carried out a series of experiments in a SCWFB, and a dual-capacitance probe measurement system was applied to measure the hydrodynamics of slugs, such as the slug frequency, chord length, and rising velocity. Four groups of Geldart-B particles with different mean diameters were fluidized by supercritical water with a system pressure of 20–27 MPa and at 410–570 °C. The minimum slugging Reynolds number increases logarithmically with Archimedes number and a predicting correlation of the minimum slugging fluidization velocity in the SCWFB is presented: R e ms = 32908 .84 ln A r 0 .55 + 260376 .65 − 410361 .90 . The relative error of the above correlation was within ±15% and the averaged relative error was 7.5%. The effect of operating conditions on the minimum slugging fluidization velocity is discussed. This research provides useful guidance for scaling-up design and for determining the optimum range of operating conditions in the SCWFB.

Any scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

Knowledge on regime transition from conventional to circulating fluidization is important to scale-up and operation of liquid-solid fluidized systems in industrial applications. Previous experimental studies reported that the onset velocity measured by bed empty time test is pertinent to the physical properties of particle and liquid, and independent of solid inventory, bed geometry, and configuration. The effect of liquid properties is, however, not clear yet since tap water is usually used as the working fluid in laboratory test for convenience. To address this problem, a Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model is applied to numerically measure the onset velocity of particles in different liquid media. The model is first validated in terms of the experimental data of bed expansion in literature. Then several kinds of particles and three kinds of liquid media of different densities and viscosities are further simulated. We find that the Reynolds number based on onset velocity and Archimedes number follows a power-law relationship. With the decrease of Archimedes number, the discrepancy of Reynolds number based on onset velocity and that on particle terminal velocity becomes highly significant. The ratio of the onset velocity to particle terminal velocity for various particles in one liquid medium is not a constant, and instead dependent on both the particle and liquid properties.

In this contribution, a three-dimensional prismatic spouted bed for coating and granulation purposes is investigated. To determine the influence of a particle size distribution on the spouting behavior, binary and ternary mixtures of different particle sizes (γ-Al2O3 particles) are used. The stability is quantified using the Fourier transforms of the pressure drop signals. The stability range of binary and ternary systems differs from the monodisperse systems. Both the lower and the upper velocity limits of stable spouting can be described by a power function dependent on the Reynolds number and the Archimedes number. A larger Archimedes number results in an increased Reynolds interval size of stable spouting, which refers to a larger size of the velocity interval. This correlation was found to be not valid for the mass equivalent mixture of three particle fractions where no stable spouting state was obtained. In addition, clustering and segregation effects were observed: Coarse particles accumulate in the spout and fine particles in the annulus region of the regarded prismatic spouted bed in case of the instable spouting regime. This is problematic for granulation and coating processes as a homogeneous droplet distribution and a proper mixing between spraying and drying zones is disabled if some particle fractions are inhibited to pass the spray zone.

The amount of particulate matter (PM) in the environment has been confirmed to be health risks on human bodies[1, 2], and therefore removing suspended particles has become the research goal of many studies. Electrostatic precipitator (ESP) is one of the high-efficiency particle collection technologies[3-7]. Particle Image Velocimetry (PIV) has been an effective tool for visualizing the flow patterns in experimental fluid mechanics, and many studies adopted this technique to study flows in ESP[8-10]. However, particles charged by the electric field can cause deviation in measurement results since it does not follow the ionized air flow which can be charged differently from the tracer particles. In this study, the observation of the effects of different particle properties on flow field in a two-stage ESP is the objectives of this study. A two-stage ESP was built and four different seeding particles, aluminum oxide (Al2O3) particle, oil droplet particle, sodium chloride (NaCl) particle, and titanium dioxide (TiO2) particle, are tested in the current study. In this study, the streamwise velocity of the flows ranges from 2.36 m/s to 4.18 m/s, the voltage of the corona electrode varies from 8 kV to 12 kV with a positive polarity, and the voltage of the collector electrode is fixed at 16 kV. To investigate the 3-D flow patterns inside the channel, data at different planes were taken for comparison. The results show that by increasing charge voltage from 8 kV to 12 kV with a streamwise flow velocity the 2.36 m/s, the y-component velocity for Al2O3 particle, oil droplet particle, NaCl particle and TiO2 particle increased by 50.6%, 76.0%, 33.5% and 51.9%, respectively. Moreover, for the case of the 4.18 m/s primary flow, the y-component velocity for Al2O3 particle, oil droplet particle, NaCl particle and TiO2 particle increase by 52.7%, 59.2%, 59.4% and 65.9% after the voltages increase from 8 kV to 12 kV. PIV results for oil droplet particle shows slower y-component velocities, which can be due to the lower Archimedes number of 3.12E-06 and the mobility number that is larger than 3. On the contrary, in most of results from TiO2 particles show high y-component velocity, which is due to the highest Archimedes number of 1.15E-03 of the seeding particles tested in this study. This result shows that the particle is less affected by buoyancy effect. The PIV results of the middle plane also shows that the ycomponent of velocity from -2.6 m/s to -0.5 m/s, in contrast to -1.0 m/s to 1.0 m/s from the near wall observation plane. These results are consistent to simulation results of the electric field distribution, whichshows unequal electric field strengths between the middle and near wall regions of the test section. Only half of the cage shape distribution of the electric field can be observed, and primary flow influences the ionic wind to move to the downstream area. Based on the results, the oil droplet and TiO2 particles are more suitable for the role of tracer particles compared to aluminum oxide and sodium chloride particles.

Various dimensionless characterizations of the solid-fluid situation during settling of a spherical particle are surveyed and related to the Archimedes number. The new landmark drag correlation developed recently is rearranged into a quadratic equation of the terminal Reynolds number. Its solution is an explicit equation of the terminal velocity of a settling sphere depending only on the Archimedes number. This new relationship is compared with a few other explicit relations existing in the literature to predict the terminal Reynolds number of spheres.

Using the Eulerian-Eulerian two-fluid model (TFM) the hydrodynamics and heat transfer around different immersed bodies in a fluidized bed were analyzed. The kinetic theory of granular flow (KTGF) was used to simulate the solid phase. For hydrodynamic simulations, 3D, 2D Cartesian and 2D axisymmetric frameworks were examined and the differences in the results of these simulations were discussed. For the heat transfer analysis, due to the high computational demand of 3D simulations, the analyses were performed using 2D Cartesian and axisymmetric frameworks. For studying the effect of shape on the CFD results, two cases of spherical and cylindrical immersed bodies were simulated. In addition, two methods for calculating the surface-to-bed heat transfer coefficient (HTC) for 2D Cartesian and axisymmetric models were examined. The first (method I) is based on constant heat flux boundary condition, while the second one (method II) is based on the isothermal wall boundary condition. It was found that method I outperforms the second one for both 2D Cartesian and axisymmetric configurations in prediction of average HTC. It was shown that the simulation results were in closed agreement with the corresponding measured data. The findings revealed that the spherical immersed body, which has a better aerodynamic shape, produced higher HTC in bubbling fluidized bed with Geldart B particles. Finally, the impact of Archimedes number (Ar) on the surface-to-bed HTC was studied.

Knowledge of the division of gas flow between the bubble and dense phases is important for modelling and operation of bubbling fluidized beds. The two-phase theory of fluidization, which suggested that the bubble flow rate being equal to the excess gas flow above the incipient fluidization, has been proved to be an overestimation in most cases. While the two-phase theory has been modified by introducing a correction factor (Y), most previous studies were conducted for Geldart Group A powders. In the present work, the contribution to predict the parameter Y for Geldart Group B and D particles has been formulated based on almost all the available experimental data. The experimental results demonstrated that the Y value increases with decreasing particle size or density and increasing excess gas velocity. A new correlation has been developed to estimate the Y value for Geldart Group B and D particles Y = 1.72 Ar − 0.133 U g − U mf 0.024 with an overall standard deviation of 19%. It only requires the knowledge of Archimedes number and excess gas velocity. This correlation is in reasonable agreement with almost all the available data in literature and the present work.

Experimental measurements of the force and torque on freely settling fibres are compared with predictions of the slender-body theory of Khayat & Cox (J. Fluid Mech., vol. 209, 1989, pp. 435–462). Although the flow is viscous dominated at the scale of the fibre diameter, fluid inertia is important on the scale of the fibre length, leading to inertial torques which tend to rotate symmetric fibres toward horizontal orientations. Experimentally, the torque on symmetric fibres is inferred from the measured rate of rotation of the fibres using a quasi-steady torque balance. It is shown theoretically that fibres with an asymmetric radius or mass density distribution undergo a supercritical pitch-fork bifurcation from vertical to oblique settling with increasing Archimedes number, increasing Reynolds number or decreasing asymmetry. This transition is observed in experiments with asymmetric mass density and we find good agreement with the predicted symmetry breaking transition. In these experiments, the steady orientation of the oblique settling fibres provides a means to measure the inertial torque in the absence of transient effects since it is balanced by the known gravitational torque.

Supercritical water fluidized bed (SCWFB) is a newly developed reactor for coal and biomass gasification without releasing pollutants. The knowledge of two-phase flow properties in SCWFB is still lacked so far in literatures due to the extreme operating condition of high-pressure and high-temperature supercritical water. In this paper, a special dual-capacitance probe measurement system is developed for the extreme flow environment in SCWFB. It is found that the linear relationship is more precise in converting the capacitance of the probe sensor into local volume fraction of solids in SCWFB than Bottcher relationship. With the help of the newly-developed dual-capacitance probe measurement system, an experimental study on the bubbling fluidization in a SCWFB is carried out when the system pressure is in the range of 20–27 MPa and the system temperature is in the range of 410–570 °C. Four groups of quartz sands with different mean diameters which belong to Geldart type B classification are fluidized. It is found that the bed expansion method which was used in literatures to identify the onset of bubbling fluidization in supercritical carbon dioxide fluidized bed doesn’t have enough precision in a SCWFB. To solve this problem, a new method of identifying the onset of bubbling fluidization in SCWFB is proposed. The minimum bubbling Reynolds number increases with the Archimedes number in a logarithmic relationship in SCWFB. At last, a new predicting correlation of the minimum bubbling fluidization velocity in SCWFB is proposed: R e mb = 26.709 ln ( A r + 10253.88 ) - 247.339 , 1900 A r 180000 The relative error of the new predicting correlation is within ±20% and the averaged relative error is 7.5%. The research work in this paper provides useful guidance for the optimization and operation of SCWFB reactor.

Temperature measurements combined with Particle Image Velocimetry (PIV) were performed in a cuboidal convection sample with a square cross section (width / height). The objective of the study is to analyze the influence of the aspect ratio Γ x z = L / H and the Archimedes number Ar on the large-scale coherent structures in mixed convection. Air at ambient pressure was used as working fluid ( P r = 0.7 ). The aspect ratio was varied between 1 ≤ Γxz ≤ 4 (length / height) and the variation of the Archimedes number was achieved by prescribing the inflow velocity of an air jet, which was superimposed on the thermally induced flow via an inlet and outlet channel. The Rayleigh number was kept constant at R a = 2.0 × 10 8 . A model, adopted from pure thermal convection, was used to extract the number of convection rolls from the circumferential temperature distribution measured along the sidewalls of the convection sample. For a fixed Archimedes number (Ar ≈ 4), the number of thermally induced large-scale circulations (LSCTC) increased with the aspect ratio of the sample. Specifically, starting with Γ = 2 , a linear dependence with unity slope was found. A decrease of the Archimedes number led to a transition from the single LSCTC structures to FC-dominated LSCs (LSCFC) for Γ = 1 and Γ = 2 , whereas the multi-roll structures found for Γ = 3 and Γ = 4 were more stable even for higher inflow velocities.

Minimum fluidization velocity is one of the most important fluidization characteristics when applying an Air Dense Medium Fluidized Bed to dry coal beneficiation. Measurements were carried out for magnetite particles (150–300 μm) and the binary mixtures of magnetite mixed with sand/gangue/coal particles (300–425 μm) to determine the influence of bed inventory on the characteristics at incipient fluidization state. The experimental results demonstrate that the minimum fluidization velocities of both single and binary mixtures of solid particles increase with increasing bed mass, which has not properly accomplished by the existing equations. The correlation proposed by Wen and Yu has been modified to predict the minimum fluidization velocity as a function of bed inventory. It only requires the knowledge of Archimedes number and the pressure drop of fluidized bed. This correlation is in reasonable agreement with almost all available data in the literature and the present work.

A method for estimating minimum fluidisation velocities in a well-mixed, bidisperse fluidised bed of spherical particles is described where a drag model iscombined with a particle packing model. The method described does not require empirical input about a specific particle mixture, and so these minimum fluidisation velocities can be estimated over wide ranges of size and densityratios. The treatment is fully non-dimensionalised. It is shown that two minimum fluidisation velocities may be defined for a well mixed bi-disperse bed:the gas speed at which fluidisation initiates determined from considering the bed as a whole, and a higher one corresponding to the balance of forces onan individual particle. The differences between bi- and mono-disperse beds arethe change in particle volume fraction owing to packing, the difference in dragaround individual particles compared with the average drag, and the action ofthe hydrostatic pressure gradient. The latter two effects tend to increase thedifference between the two limits of minimum fluidisation velocity, while packing decreases it and intensifies the dependence on mass fraction of the minimumfluidisation velocities. The influence of inertia is determined from particle properties through an Archimedes number. Though the inertial effects are not large for a wide range of particles, they can start to dominate other influences on the minimum fluidisation velocities as particle diameter increases.

The characteristic features of the motion of single particles in a swirled gas flow are considered. A dependence has been obtained for calculating the maximum height of particle ascent. An extreme dependence of the time taken by the particle to reach the chamber walls on its diameter has been established.

The objective of this research was to develop and analyze the procedure for using recent air infiltration (AI) data collected from commercial swine finishing rooms (SFRs) in the design of negative pressure mechanical ventilation systems (VSs). Air infiltration is an integral part of any ventilation process. Infiltration reduces the pressure differential across planned inlets and at very low pressure differences, cold air jets may drop directly on the animals causing significant discomfort. In this article, a design procedure is proposed for swine housing ventilation systems with the influence of air infiltration included. The method was used on one SFR for which air infiltration data was collected by in-field testing. The air-jet throw, jet momentum number, a newly developed coverage factor, and Archimedes number were used to assess the influence of infiltration on predicted air-jet and fresh-air distribution and to help guide the design of planned inlets in SFR VSs with known infiltration. The analysis completed quantifies the severity of AI on air-jet and air distribution performance, and suggests that for the analysis room to ventilate properly requires a 50% reduction in AI levels beyond field measured curtain and fan infiltration. The analysis completed suggests a method for systematically planning three-dimensional ceiling inlet placement and operation and provides design guidance for new ceiling inlets suitable for SFR VSs. Keywords: Air distribution, Air-jets, Archimedes number, Infiltration, Jet Momentum Number.