Готові списки джерел за темами / Particle Reynolds Number

Добірка наукової літератури з теми "Particle Reynolds Number"

Автор: Grafiati
Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Particle Reynolds Number"

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Chen, Rongqian, Yi Liu, and Deming Nie. "Computer Simulation of Three Particles Sedimentation in a Narrow Channel." Mathematical Problems in Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/1259840.

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The settling of three particles in a narrow channel is simulated via the lattice Boltzmann direct-forcing/fictitious domain (LB-DF/FD) method for the Reynolds number ranging from 5 to 200. The effects of the wall and the Reynolds number are studied. It is interesting to find that at certain Reynolds numbers the left (right) particle is settling at 0.175 (0.825) of the channel width irrespective of its initial position or the channel width. Moreover, numerical results have shown that the lateral particles lead at small Reynolds numbers, while the central particle leads at large Reynolds numbers due to the combined effects of particle-particle and particle-wall interactions. The central particle will leave the lateral ones behind when the Reynolds number is large enough. Finally the effect of the Reynolds number on the trajectory of the lateral particles is presented.
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2

Mao, Wenbin, and Alexander Alexeev. "Motion of spheroid particles in shear flow with inertia." Journal of Fluid Mechanics 749 (May 14, 2014): 145–66. http://dx.doi.org/10.1017/jfm.2014.224.

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AbstractIn this article, we investigate the motion of a solid spheroid particle in a simple shear flow. Using a lattice Boltzmann method, we examine individual effects of fluid inertia and particle rotary inertia as well as their combination on the dynamics and trajectory of spheroid particles at low and moderate Reynolds numbers. The motion of a single spheroid is shown to be dependent on the particle Reynolds number, particle aspect ratio, particle initial orientation and the Stokes number. Spheroids with random initial orientations are found to drift to stable orbits influenced by fluid inertia and/or particle inertia. Specifically, prolate spheroids drift towards the tumbling mode of motion, whereas oblate spheroids drift to the rolling mode. The rotation period and the variation of angular velocity of tumbling spheroids decrease as Stokes number increases. With increasing Reynolds number, both the maximum and minimum values of angular velocity decrease, whereas the particle rotation period increases. We show that particle inertia does not affect the hydrodynamic torque on the particle. We also demonstrate that superposition can be used to estimate the combined effect of fluid inertia and particle inertia on the dynamics of spheroid particles at sufficiently low Reynolds numbers.
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DANIEL, W. BRENT, ROBERT E. ECKE, G. SUBRAMANIAN, and DONALD L. KOCH. "Clusters of sedimenting high-Reynolds-number particles." Journal of Fluid Mechanics 625 (April 14, 2009): 371–85. http://dx.doi.org/10.1017/s002211200900620x.

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We report experiments wherein groups of particles were allowed to sediment in an otherwise quiescent fluid contained in a large tank. The Reynolds number of the particles, defined as Re = aU/ν, ranged from 93 to 425; here, a is the radius of the spherical particle, U its settling velocity and ν the kinematic viscosity of the fluid. The characteristic size of a cluster, in a plane transverse to gravity, was measured by a ‘cluster variance’(〈r2t〉); the latter is defined as the mean square of the transverse coordinates of all constituent particles, averaged over a series of runs. The cluster variance, when plotted as a function of time, exhibited two regimes. There was a quadratic growth in the variance at short times(〈r2t〉 ∝ t2), while for long times, the cluster variance exhibited a slower sublinear growth with 〈r2t〉 ∝ t0.67. A theory, based on isotropic repulsive hydrodynamic interactions between particles, predicts the cluster variance to grow as t2/3 in the limit of long times. The theoretical framework was originally proposed to describe the long-time self-similar evolution of dilute clusters in the limit Re ≪ 1 Subramanian & Koch (J. Fluid Mech., vol. 603, 2008, p. 63), when the probability of wake-mediated interactions between particles remains asymptotically small; the latter requirement is satisfied for homogeneous spherical clusters larger than a critical radius, and is evidently satisfied for planar clusters oriented transversely to gravity. The isotropy of the interactions therefore stems from the isotropy, at large distances, of the disturbance velocity field produced by a single sedimenting particle outside its wake(which contains the compensating inflow to satisfy mass conservation). Herein, the theory is extended to large Re using an empirical correlation for the drag on a sedimenting particle. This allows one to predict, as a function of Re, the numerical prefactors in the expressions for the cluster variance of both spherical and planar clusters; the predictions for the growth exponent remain unchanged. The agreement between the theoretical and experimental growth exponents supports the hypothesis of a self-similar expansion at long times. The prefactor determined from the experimental observations is found to lie between the theoretical predictions for planar and spherical clusters.
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4

Nie, Deming, Jianzhong Lin, and Mengjiao Zheng. "Direct Numerical Simulation of Multiple Particles Sedimentation at an Intermediate Reynolds Number." Communications in Computational Physics 16, no. 3 (September 2014): 675–98. http://dx.doi.org/10.4208/cicp.270513.130314a.

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AbstractIn this work the previously developed Lattice Boltzmann-Direct Forcing/ Fictitious Domain (LB-DF/FD) method is adopted to simulate the sedimentation of eight circular particles under gravity at an intermediate Reynolds number of about 248. The particle clustering and the resulting Drafting-Kissing-Tumbling (DKT) motion which takes place for the first time are explored. The effects of initial particle-particle gap on the DKT motion are found significant. In addition, the trajectories of particles are presented under different initial particle-particle gaps, which display totally three kinds of falling patterns provided that no DKT motion takes place, i.e. the concave-down shape, the shape of letter “M” and “in-line” shape. Furthermore, the lateral and vertical hydrodynamic forces on the particles are investigated. It has been found that the value of Strouhal number for all particles is the same which is about 0.157 when initial particle-particle gap is relatively large. The wall effects on falling patterns and particle expansions are examined in the final.
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Mei, Renwei, and Ronald J. Adrian. "Effect of Reynolds Number on Isotropic Turbulent Dispersion." Journal of Fluids Engineering 117, no. 3 (September 1, 1995): 402–9. http://dx.doi.org/10.1115/1.2817276.

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The influence of the spatio-temporal structure of isotropic turbulence on the dispersion of fluid and particles with inertia is investigated. The spatial structure is represented by an extended von Ka´rma´n energy spectrum model which includes an inertial sub-range and allows evaluation of the effect of the turbulence Reynolds number, Reλ. Dispersion of fluid is analyzed using four different models for the Eulerian temporal auto-correlation function D(τ). The fluid diffusivity, normalized by the integral length scale L11 and the root-mean-square turbulent velocity u0, depends on Reλ. The parameter cE = T0u0/L11, in which T0 is the Eulerian integral time scale, has commonly been assumed to be constant. It is shown that cE strongly affects the value of the fluid diffusivity. The dispersion of a particle with finite inertia and finite settling velocity is analyzed for a large range of a particle inertia and settling velocity. Particle turbulence intensity and diffusivity are influenced strongly by turbulence structure.
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6

Tu, Chengxu, and Jian Zhang. "Nanoparticle-laden gas flow around a circular cylinder at high Reynolds number." International Journal of Numerical Methods for Heat & Fluid Flow 24, no. 8 (October 28, 2014): 1782–94. http://dx.doi.org/10.1108/hff-03-2013-0101.

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Purpose – Experiments to investigate the characteristic distribution of nanoparticle-laden gas flow around a circular cylinder were performed with a fast mobility particle spectrometer. The paper aims to discuss these issues. Design/methodology/approach – The fast mobility particle sizer spectrometer is used to measure quasi-instantaneous particle number density. The acquired particle number density, total concentration, and geometric mean diameter at free stream and in the wake were used to discuss the particle characteristic distribution. The time-averaged velocity field detected by particle imaging velocimetry was used to investigate the effect of carried phase on nanoparticles distribution. Findings – Results show that the total particle concentration in the free stream is larger than that in the wake. However, the geometric mean diameter of particle in the free stream is smaller than that in the wake for different Re. The total particle concentration and geometric mean diameter in the free stream and the wake both change in the same way, but with an obvious lag which increases with Re. Despite particle deposition, the number density of particles with electrical-mobility-equivalent diameters in the range from 220.7 to 523.3 nm in the wake is still higher than that in the free stream. Originality/value – Though the particles-laden gas flow around a circular cylinder had been studied experimentally and numerically before, where particles are larger than one micrometer, investigators paid little attention on the nanoparticles-laden gas flow where particles are smaller than one micrometer, especially at high Reynolds number, because numerical methods so far cannot deal these problems completely and satisfactorily. However, this issue is widely existing in nature and engineering application, such as superfine dust or microorganism captured by a circular cylinder model.
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Almerol, Jenny Lynn Ongue, and Marissa Pastor Liponhay. "Clustering of fast gyrotactic particles in low-Reynolds-number flow." PLOS ONE 17, no. 4 (April 7, 2022): e0266611. http://dx.doi.org/10.1371/journal.pone.0266611.

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Systems of particles in turbulent flows exhibit clustering where particles form patches in certain regions of space. Previous studies have shown that motile particles accumulate inside the vortices and in downwelling regions, while light and heavy non-motile particles accumulate inside and outside the vortices, respectively. While strong clustering is generated in regions of high vorticity, clustering of motile particles is still observed in fluid flows where vortices are short-lived. In this study, we investigate the clustering of fast swimming particles in a low-Reynolds-number turbulent flow and characterize the probability distributions of particle speed and acceleration and their influence on particle clustering. We simulate gyrotactic swimming particles in a cubic system with homogeneous and isotropic turbulent flow. Here, the swimming velocity explored is relatively faster than what has been explored in other reports. The fluid flow is produced by conducting a direct numerical simulation of the Navier-Stokes equation. In contrast with the previous results, our results show that swimming particles can accumulate outside the vortices, and clustering is dictated by the swimming number and is invariant with the stability number. We have also found that highly clustered particles are sufficiently characterized by their acceleration, where the increase in the acceleration frequency distribution of the most clustered particles suggests a direct influence of acceleration on clustering. Furthermore, the acceleration of the most clustered particles resides in acceleration values where a cross-over in the acceleration PDFs are observed, an indicator that particle acceleration generates clustering. Our findings on motile particles clustering can be applied to understanding the behavior of faster natural or artificial swimmers.
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Heymsfield, Andrew, and Robert Wright. "Graupel and Hail Terminal Velocities: Does a “Supercritical” Reynolds Number Apply?" Journal of the Atmospheric Sciences 71, no. 9 (August 28, 2014): 3392–403. http://dx.doi.org/10.1175/jas-d-14-0034.1.

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Abstract This study characterizes the terminal velocities of heavily rimed ice crystals and aggregates, graupel, and hail using a combination of recent drag coefficient and particle bulk density observations. Based on a nondimensional Reynolds number (Re)–Best number (X) approach that applies to atmospheric temperatures and pressures where these particles develop and fall, the authors develop a relationship that spans a wide range of particle sizes. The Re–X relationship can be used to derive the terminal velocities of rimed particles for many applications. Earlier observations suggest that a “supercritical” Reynolds number is reached where the drag coefficient for large spherical ice—hail—drops precipitously and the terminal velocities increase rapidly. The authors draw on observations and model simulations for slightly roughened large ice particles that suggest that the critical Reynolds number is dampened and that the rapid increase in the terminal velocity of smooth spherical ice particles rarely occurs for natural hailstones.
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Wu, Zhenqun, Hui Jin, and Leijin Guo. "Investigation on the drag coefficient of supercritical water flow past sphere-particle at low reynolds numbers." Thermal Science 21, suppl. 1 (2017): 217–23. http://dx.doi.org/10.2298/tsci17s1217w.

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Supercritical water fluidized bed is novel reactor for the efficient gasification of coal to produce hydrogen. The Euler-Euler and Euler-Lagrange methods can be used to simulate the flow behaviors supercritical water fluidized bed. The accuracy of the simulated results with the two methods has a great dependence on the drag coefficient model, and there is little work focused on the study on particle?s drag force in supercritical water. In this work, the drag coefficients of supercritical water flow past a single particle and particle cluster. The simulated results show that the flow field and drag coefficient of single particle at supercritical condition have no difference to that at ambient conditions when the Reynolds number is same. For the two-particles model, a simplification of particle cluster, the drag coefficients of the two particles are identical at different conditions for the same Reynolds number. The variation characteristics with the Reynolds number and particles? positions are also same.
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10

Espinosa-Gayosso, Alexis, Marco Ghisalberti, Gregory N. Ivey, and Nicole L. Jones. "Particle capture and low-Reynolds-number flow around a circular cylinder." Journal of Fluid Mechanics 710 (September 7, 2012): 362–78. http://dx.doi.org/10.1017/jfm.2012.367.

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AbstractParticle capture, whereby suspended particles contact and adhere to a solid surface (a ‘collector’), is an important mechanism in a range of environmental processes. In aquatic systems, typically characterized by low collector Reynolds numbers ($\mathit{Re}$), the rate of particle capture determines the efficiencies of a range of processes such as seagrass pollination, suspension feeding by corals and larval settlement. In this paper, we use direct numerical simulation (DNS) of a two-dimensional laminar flow to accurately quantify the rate of capture of low-inertia particles by a cylindrical collector for $\mathit{Re}\leq 47$ (i.e. a range where there is no vortex shedding). We investigate the dependence of both the capture rate and maximum capture angle on both the collector Reynolds number and the ratio of particle size to collector size. The inner asymptotic expansion of Skinner (Q. J. Mech. Appl. Maths, vol. 28, 1975, pp. 333–340) for flow around a cylinder is extended and shown to provide an excellent framework for the prediction of particle capture and flow close to the leading face of a cylinder up to $\mathit{Re}= 10$. Our results fill a gap between theory and experiment by providing, for the first time, predictive capability for particle capture by aquatic collectors in a wide (and relevant) Reynolds number and particle size range.
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Дисертації з теми "Particle Reynolds Number"

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Vargas-Dilaz, Salvador. "Numerical simulations of hydrodynamic particle interactions at low particle Reynolds number." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/11500.

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When solid particles are suspended in the fluid and are not in a jammed state, a fruitful approach to modelling the system can be to describe it as a system of particles interacting both with each other and with an external field. In the specific case when the particles are far enough apart, the dominant interactions between particles are those mediated by the surrounding fluid rather than direct particle-particle interactions, possibly only when the particles are touching. One of the most important phenomena observed in this regime is particle roping – rather than being evenly dispersed throughout the fluid, particles congregate in one or more ‘ropes’ aligned with the flow direction. This can be a serious problem in coal fired power stations, which require coal dust to be evenly distributed to operate at maximum efficiency. This thesis presents a basic numerical study of particle-fluid-particle interactions under conditions characteristic of the roping phenomenon found after bends in the pneumatic transport systems of coal fired power plants. The main objectives of this work are to: 1. Obtain a pair potential hydrodynamic force field from computational fluid dynamics (CFD) simulations of two fixed spherical particles at low particle Reynolds number; 2. Estimate the magnitude of errors introduced by the pair potential approximation by comparing the two fixed spherical particles results with CFD simulations of systems of three fixed spherical particles; and 3. Use many-particle Monte Carlo simulations to investigate the conditions under which clustering or roping occurs.
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Stoos, James Arthur Leal L. Gary Leal L. Gary Herbolzheimer Eric. "Particle dynamics near fluid interfaces in low-Reynolds number flows /." Diss., Pasadena, Calif. : California Institute of Technology, 1988. http://resolver.caltech.edu/CaltechETD:etd-02022007-110333.

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Staben, Michelle Elizabeth. "Low-Reynolds-number particle transport in narrow channels for microfluidics and other applications." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3178360.

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Hammer, Patrick Richard. "A Discrete Vortex Method Application to Low Reynolds Number Aerodynamic Flows." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1311792450.

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5

Hashemi, Mohammadabad Saeed. "Collision efficiency of a pollutant particle onto a long cylinder in low Reynolds number fluid flow." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24057.

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A method for calculating the collision efficiency of a small pollutant particle onto a solid long circular cylinder in a low Reynolds number fluid flow with inertia affects is presented. The cylinder is considered at rest in a uniform undisturbed flow at infinity, in the direction perpendicular to the cylinder axis.
Assuming that the Reynolds number R based on cylinder radius b is very small but not zero ($R ll 1$), and the Reynolds number Re based on cylinder length l is of order unity, the force per unit length of the cylinder, correct to the order of R, is obtained, first for a general flow direction and then for the case of flow perpendicular to the cylinder axis. This is done by using the Naiver-Stokes equations in long slender bodies theory and applying matched asymptotic expansions in terms of the ratio $ kappa$ of radius to body length. Flow field around the cylinder is calculated and the equation of particle motion is developed by applying Newton's second law of motion. The initial particle velocity far from the cylinder is calculated analytically and the particle trajectory course is solved numerically as an initial value problem by using Richardson Extrapolation and the Bulirsch-Stoer method.
The collision Efficiency E is obtained by trial and error and is plotted against the dimensionless particle parameter p for different values of R (from 10$ sp{-6}$ to 1). The numerical calculations show that the curves have a tendency to move to the right and become like a straight-line as R gets very small. The points at which E is less than 0.005 are also predicted.
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6

Clark, Thomas Henry. "Measurement of three-dimensional coherent fluid structure in high Reynolds number turbulent boundary layers." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243622.

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The turbulent boundary layer is an aspect of fluid flow which dominates the performance of many engineering systems - yet the analytic solution of such flows is intractable for most applications. Our understanding of boundary layers is therefore limited by our ability to simulate and measure them. Tomographic Particle Image Velocimetry (TPIV) is a recently developed technique for direct measurement of fluid velocity within a 3D region. This allows new insight into the topological structure of turbulent boundary layers. Increasing Reynolds Number increases the range of scales at which turbulence exists; a measurement technique must have a larger 'dynamic range' to fully resolve the flow. Tomographic PIV is currently limited in spatial dynamic range (which is also linked to the spatial and temporal resolution) due to a high degree of noise. Results also contain significant bias error. This work proposes a modification of the technique to use more than two exposures in the PIV process, which (for four exposures) is shown to improve random error by a factor of 2 to 7 depending on experimental setup parameters. The dynamic range increases correspondingly and can be doubled again in highly turbulent flows. Bias error is reduced by up to 40%. An alternative reconstruction approach is also presented, based on application of a reduction strategy (elimination of coefficients based on a first guess) to the tomographic weightings matrix Wij. This facilitates a potentially significant increase in computational efficiency. Despite the achieved reduction in error, measurements contain non-zero divergence due to noise and sampling errors. The same problem affects visualisation of topology and coherent fluid structures. Using Projection Onto Convex Sets, a framework for post-processing operators is implemented which includes a divergence minimisation procedure and a scale-limited denoising strategy which is resilient to 'false' vectors contained in the data. Finally, developed techniques are showcased by visualisation of topological information in the inner region of a high Reynolds Number boundary layer (δ+ = 1890, Reθ = 3650). Comments are made on the visible flow structures and tentative conclusions are drawn.
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7

Ullah, Al Habib. "Advanced Measurements and Analyses of Flow Past Three-Cylinder Rotating System." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31833.

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Interaction of flow structures from a three-cylinder system is complex and important for fundamental and engineering applications. In this study, experiments using hotwire, 2D PIV, and Tomography are to be conducted to characterize the fluid flow at various Re number and rotation speeds. The Reynolds number considered based on the diameter of the single-cylinder ranges from 37 to 1700. The peaks in the frequency spectrum obtained from the hotwire study show a unique relation of Strouhal number as a function of static incident angle, RPM, and Reynolds number. From the 2D PIV and 3D tomography experiment, vorticity and velocity results characterize the interaction of wake flow from individual cylinders and as a function of the rotational speeds. Besides, the Standard deviation map shows the turbulence intensity variation at the various static and rotating conditions. The obtained results at static conditions are found to be consistent with the previous computational study.
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Bloxham, Matthew Jon. "The effects of vortex generator jet frequency, duty cycle, and phase on separation bubble dynamics /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1760.pdf.

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Nessler, Chase A. "Characterization of Internal Wake Generator at Low Reynolds Number with a Linear Cascade of Low Pressure Turbine Blades." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1270749309.

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Sharma, Amit. "Effect of Vortex Shedding on Aerosolization of a Particle from a Hill using Large-Eddy Simulation." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617105212418248.

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Книги з теми "Particle Reynolds Number"

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Bodnar, Andrea Claire. Low Reynolds number particle-fluid interactions. Toronto: [s.n.], 1994.

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2

Bodnar, Andréa Claire. Low Reynolds number particle-fluid interactions. 1993.

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3

Happel, J., and H. Brenner. Low Reynolds Number Hydrodynamics: With Special Applications to Particulate Media. Springer, 2012.

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4

Kirchman, David L. The physical-chemical environment of microbes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0003.

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Many physical-chemical properties affecting microbes are familiar to ecologists examining large organisms in our visible world. This chapter starts by reviewing the basics of these properties, such as the importance of water for microbes in soils and temperature in all environments. Another important property, pH, has direct effects on organisms and indirect effects via how hydrogen ions determine the chemical form of key molecules and compounds in nature. Oxygen content is also critical, as it is essential to the survival of all but a few eukaryotes. Light is used as an energy source by phototrophs, but it can have deleterious effects on microbes. In addition to these familiar factors, the small size of microbes sets limits on their physical world. Microbes are said to live in a “low Reynolds number environment”. When the Reynolds number is smaller than about one, viscous forces dominate over inertial forces. For a macroscopic organism like us, moving in a low Reynolds number environment would seem like swimming in molasses. Microbes in both aquatic and terrestrial habitats live in a low Reynolds number world, one of many similarities between the two environments at the microbial scale. Most notably, even soil microbes live in an aqueous world, albeit a thin film of water on soil particles. But the soil environment is much more heterogeneous than water, with profound consequences for biogeochemical processes and interactions among microbes. The chapter ends with a discussion of how the physical-chemical environment of microbes in biofilms is quite different from that of free-living organisms.
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Частини книг з теми "Particle Reynolds Number"

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Yeung, P. K., Shuyi Xu, M. S. Borgas, and B. L. Sawford. "Scaling of Multi-Particle Lagrangian Statistics in Direct Numerical Simulations." In IUTAM Symposium on Reynolds Number Scaling in Turbulent Flow, 163–68. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-007-0997-3_28.

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2

Henniger, R., and L. Kleiser. "Reynolds Number Influence on the Particle Transport in a Model Estuary." In ERCOFTAC Series, 263–68. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2482-2_42.

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3

Tsuji, Yoshiyuki, Jens H. M. Pransson, P. Henrik Alfredsson, and Arne V. Johansson. "Shear Effect on Pressure and Particle Acceleration in High-Reynolds-Number Turbulence." In IUTAM Symposium on Computational Physics and New Perspectives in Turbulence, 177–82. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6472-2_27.

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4

Atkinson, Callum, Sebastien Coudert, Jean-Marc Foucaut, Michel Stanislas, and Julio Soria. "Tomographic Particle Image Velocimetry Measurements of a High Reynolds Number Turbulent Boundary Layer." In ERCOFTAC Series, 113–20. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-9603-6_12.

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Dunnett, Sarah Jane, and Derek Binns Ingham. "The Effects of the Particle Reynolds Number on the Aspiration of Particles Into a Blunt Sampler." In Lecture Notes in Engineering, 101–15. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83563-6_6.

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Yao, Zishun, Lidi Shi, Shoupeng Xie, Peng Li, and Dawei Guan. "Experimental Study on Flow Characteristics Around a Submerged Half-Buried Pipeline." In Lecture Notes in Civil Engineering, 74–81. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_7.

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AbstractThis paper describes the flow characteristics around a half-buried pipeline exposed to different current conditions by flume experiment. Particle Imaging Velocimetry (PIV) technique was used in the experiment to reveal the flow structure. The experiment results indicate that the hydrodynamic parameters, including average kinetic energy, vorticities, Reynolds shear stress, and kinetic turbulence energy, increased with the Renolds numbers. Furthermore, it is found that the vortex at the upstream side of the half-buried pipeline vanishes gradually with increasing Renolds numbers. However, the two vortices at the locations downstream of the half-buried pipeline exist all the time, in which the vortex closed to the downstream of the pipeline becomes unstable, the vortex at the pipeline wake remains unchanged. In the meantime, the turbulence intensity at the upstream side of the half-buried pipe near the bed surface strengthens significantly under Reynolds number conditions, which may accelerate the potential scour process in front of the pipeline.
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Salvetti, Maria Vittoria, Cristian Marchioli, and Alfredo Soldati. "Particle Dispersion in Large-Eddy Simulations: Influence of Reynolds Number and of Subgrid Velocity Deconvolution." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 311–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14139-3_38.

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Aly, A. Abou El-Azm, F. Nicolleau, and A. ElMaihy. "Effect of the Reynolds number and initial separation on multi-particle sets using Kinematic Simulations." In Springer Proceedings Physics, 106–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-72604-3_32.

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Westerweel, J., R. J. Adrian, J. G. M. Eggels, and F. T. M. Nieuwstadt. "Measurements with Particle Image Velocimetry on Fully Developed Turbulent Pipe Flow at Low Reynolds Number." In Laser Techniques and Applications in Fluid Mechanics, 285–307. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-662-02885-8_18.

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Cheng, Zhongfu, and Miaoyong Zhu. "Motion Characteristics of a Powder Particle through the Injection Device with Slats at Finite Reynolds Number." In Materials Processing Fundamentals, 291–303. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118662199.ch33.

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Тези доповідей конференцій з теми "Particle Reynolds Number"

1

Li, Zhenzhong, Jinjia Wei, and Bo Yu. "Numerical Simulations of Particle-Laden Flow Based on Given Friction Reynolds Number and Mean Reynolds Number Respectively." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21332.

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Multiphase flow with particles covers a wide spectrum of flow conditions in natural world and industrial applications. The experiments and the direct numerical simulation have become the most popular means to study the dilute particle-laden flow in the last two decades. In the experimental study, the mean Reynolds number is often adjusted to the value of single-phase flow for each set of particle conditions. However, the friction Reynolds number usually keeps invariable in the direct numerical simulation of the particle-laden flows for convenience. In this study the effect of the difference between given mean Reynolds number and friction Reynolds number was investigated. Two simulations were performed for each set of particle parameters, and the mean Reynolds number and friction Reynolds number were kept invariant respectively. From the results it can be found that the turbulence intensity and the dimensionless velocities are larger when keeping the friction Reynolds constant. And the results calculated from the cases of keeping the mean Reynolds number invariable agree with the experiment results better. In addition, the particle distribution along the wall-normal coordinate was found to be unchanged between two simulation conditions. As a suggestion, keeping the same mean Reynolds number in the direct numerical simulation of particle-laden flow is more appropriate.
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Smart, M., Derrick O. Njobuenwu, and M. Fairweather. "Reynolds number effect on particle-laden channel flows." In THMT-12. Proceedings of the Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo, Italy, 24-27 September, 2012. Connecticut: Begellhouse, 2012. http://dx.doi.org/10.1615/ichmt.2012.procsevintsympturbheattransfpal.1130.

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3

Li, C. J., H. L. Liao, P. Gougeon, G. Montavon, and C. Coddet. "Experimental Correlation between Flattening Degree and Reynolds Number of Spray Particles." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p0863.

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Abstract The particle parameters including particle size, velocity and temperature influence significantly splat formation process in thermal spraying. The flattening degree of subsequent splat determines the coating structure and properties. Both theoretical analysis and simulation of splatting process indicate that the flattening degree depends on Reynolds number (Re) of spray particles. The experimental correlations suggest that the theoretical models overestimate the flattening degree. In the present study, with careful control of particle size and measurement of particle velocity and temperature, the relationship between the flattening degree and particle Reynolds number is examined experimentally. Copper powders of small size range are used to ensure valid of mean particle size. Plasma spraying is carried out under different conditions to change particle velocity and temperature. The particle velocity and temperature are measured using DPV- 2000. Splats were deposited on preheated polished stainless substrate surface. The diameter of individual splat was measured. The flattening degree was estimated using average diameter of splats and spray particles for individual spray condition. Using the exponential formula of Re with a power of 0.2, it was found that experimental correlation yielded a coefficient about half of that given by Madjeski’s model.
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Hagiwara, Yoshimichi, H. Fujii, and A. Kitagawa. "Experimental verification for the prediction of particle path and particle Reynolds number using local Stokes number." In THMT-12. Proceedings of the Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo, Italy, 24-27 September, 2012. Connecticut: Begellhouse, 2012. http://dx.doi.org/10.1615/ichmt.2012.procsevintsympturbheattransfpal.2550.

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Rahman, Mustafa M., and Ravi Samtaney. "Particle Concentration Variation for Inflow Profiles in High Reynolds Number Turbulent Boundary Layer." In ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20293.

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Abstract Large-eddy simulations (LES) of incompressible turbulent boundary-layer flows can simulate a fundamental unsteady turbulent flow, including time-variant streamwise and wall-normal velocity as well as the near-wall locations of significant turbulence intensities. A typical illustration of turbulent flows with such high Reynolds numbers can be roughly approximated to atmospheric boundary-layer flows. To bypass the demanding mesh criteria of near-ground field and direct numerical simulations, we adopt a virtual-wall model with a stretched-vortex subgrid-scale model. We simulate the dynamics of solid particles in this wall-modeled LES approach toward incompressible flow. The particles considered are both charged and uncharged, and have a fixed concentration profile with no fluctuations at the inflow. An extended streamwise simulation domain is implemented as an alternative to rerunning the simulation with a turbulent inflow profile from the simulation of the previous downstream profile. By extending the streamwise domain, the fluctuation dynamics of the particles reach a steady state far downstream from the inflow. The streamwise and altitude variation of the particle parameters are compared for various particle-concentration inflow profiles. Furthermore, an estimate of the streamwise variation of parameters is also observed. This study is the first step towards enhancing our understanding of the particle dynamics in turbulent flows.
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Curtis, Jennifer Sinclair. "Effect of Solids Loading, Reynolds Number, and Particle Size Distribution on Velocity Fluctuations in Gas-Particle Flows." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45669.

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A variety of LDV experiments were conducted to assess the influence of solids loading, Reynolds number and particle size distribution on velocity fluctuations and flow behavior in gas-particle systems. This talk will summarize those experimental findings, as well as show comparisons of experimental results with multiphase CFD model predictions that utilize concepts from kinetic theory to describe particle velocity fluctuations. In order to probe solids loading effects, an axisymmetric particle-laden jet was investigated using LDV for 70 micron glass beads with solids loadings ranging from one to thirty. Dilute conditions are characterized by isotropic particle r.m.s. velocities and decreases in the magnitude of the r.m.s. velocities as the solids loading increases. Particle clustering is observed for dense conditions as well as anisotropy between axial and radial particle r.m.s. velocities. Under dense conditions, increases in the solids loading lead to increases in the axial particle r.m.s. velocity while the radial r.m.s. velocity remains at a constant level. Gas-solids flow models display good agreement between predictions and experimental measurements of mean velocities of the gas and solids as well as modulation of the gas turbulent kinetic energy by the presence of the particles. However, the gas-solid flow models based on kinetic theory concepts consistently overpredict the particle r.m.s. velocity for the range of solids loadings investigated. In addition, the same axisymmetric particle-laden jet consisting of 70-micron glass beads was investigated for a range of Reynolds numbers with a constant mass loading (m = 0.7). The presence of the solids dampens the gas turbulence intensity at the lowest value of Re investigated (8,300) compared with single-phase flow at the same Re. As the Reynolds number increases, the gas turbulence increases and for Re ≥ 15,200 the turbulence is enhanced compared with the single-phase flow at the same Re. The observed trend in turbulence modulation with Reynolds number is possibly due to the segregation of the solids and their effect on the gas mean velocity profiles. Finally, the particle-laden jet was investigated for binary mixtures of 25 and 70-micron glass beads. Specifically, the effect of a bimodal PSD on the modulation of gas-phase turbulence, the particle rms velocity, and particle segregation patterns was explored in detail. Measurements and model predictions indicate that increasing the mass fraction of the finer particles dampens the gas-phase turbulence. Changes in the random motion of the coarser particles are observed upon the addition of the finer material; clusters of fine particles arise for the largest solids loading investigated, and these clusters increase both the mean and fluctuating velocities of the coarse particles. The particles are also observed to segregate by size and volume fraction, with the coarse particles tending towards the center of the pipe.
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Truong, Hung V., John C. Wells, and Gretar Tryggvason. "Explicit vs. Implicit Particle-Liquid Coupling in Fixed-Grid Computations at Moderate Particle Reynolds Number." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77206.

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In an attempt to develop a reliable numerical method that can deal economically with a large number of rigid particles moving in an incompressible Newtonian fluid at a reasonable cost, we consider two fictitious-domain methods: a Constant-density Explicit Volumetric forcing method (CEV) and a Variable-density Implicit Volumetric forcing method (VIV). In both methods, the mutual interaction between the solid and the fluid phase is taken into account by an additional body force term to the Navier-Stokes equations, but the physical meaning of the forcing is different for the two methods. In the CEV method, which is built on a constant-density Navier-Stokes solver, the net forcing added to the fluid is generally not zero, and must be cancelled by applying Newton’s first law to a rigid particle template which has the same shape as the rigid particle and carries the “excess mass” of the rigid particle, i.e. the excess over the mass of the displaced fluid. The “target velocity” to which one forces the velocity within the particle is evaluated through the equation of motion for the rigid particle template. In the VIV method, built on a variable-density incompressible flow solver, the rigid particle (angular) velocity is determined by averaging the (angular) momentum, within the particle domain, of the fractional-step velocity field, and the net forcing is zero. By design, this method does not require any rigid particle template equations, so it can be applied for both neutral and non-neutral density ratios without any difficulties. We consider two test problems with single freely moving circular disks: a disk falling in quiescent fluid, and a disk in Poiseuille channel flow. At near-neutral density ratios, the CEV method is found to perform better, while the VIV method yields more accurate results at higher relative density ratios.
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Pourghasemi, Mahyar, Nima Fathi, Peter Vorobieff, Goodarz Ahmadi, and Kevin R. Anderson. "Multiphase Flow Development on Single Particle Migration in Low Reynolds Number Fluid Domains." In ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20477.

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Abstract Here we present the results of the newly developed Eulerian-Lagrangian model to simulate both the primary and the secondary phases coupled in a transient analysis. A set of two a-dimensional, transient linear shear flow at low Reynolds numbers was considered, and the effect of shearing rate on a suspended buoyant spherical solid particle was analyzed. The rotation and displacement of the solid particle are considered in the model, and the effect of the secondary phase on the primary phase is also evaluated at each time step without any simplification. In order to overcome the existing discontinuity at the interface between secondary and primary phases in this Eulerian-Lagrangian approach, the interface between the solid particle and the fluid phase is replaced by a kernel function creating a smooth profile from the solid into the liquid with a predefined thickness. Several simulations were performed, and the reliability of the developed model was assessed. The global deviation grid convergence index (GCI) approach was employed to perform solution verification. The observed order of accuracy of the primary phase solver approaches 2, consistent with the formal order of accuracy of the applied discretization scheme. The obtained velocity profiles from the computational analyses show excellent agreement with the analytical solution confirming the reliability of the single-phase flow solver. To validate the computational results for the multiphase flow solver, we used the experimental data from our newly developed linear shear flow apparatus with suspended buoyant particles.
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Zaidi, Ali Abbas. "Effect of bi-dispersity on particle microstructures in settling of particles at high Reynolds number." In INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0026559.

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Bourgoyne, Dwayne A., Carolyn Q. Judge, and Joshua M. Hamel. "Hydrofoil Testing At High Reynolds Number." In SNAME 26th American Towing Tank Conference. SNAME, 2001. http://dx.doi.org/10.5957/attc-2001-015.

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Lifting surfaces are used both for propulsion and control of sea vessels and must meet performance criteria such as lift, drag, and (in some military applications) hydroacoustic noise limits. Design tools suitable to predict such criteria must handle complex flow phenomena and manage the wide range of flow scales inherent in marine applications (Reynolds numbers ~10^8). To date, the development of such tools has been limited by the lack of controlled experimental data in this high Reynolds numbers range. Lifting surface flow is the focus of current high Reynolds number experiments involving a two-dimensional hydrofoil in the world's largest water tunnel, the US Navy's William B. Morgan Large Cavitation Channel (LCC). The goal of these experiments is to provide a unique high Reynolds number experimental dataset at chord-based Reynolds numbers (Re) approaching those of full-scale propulsors ( ~ 10^8). This data will be used for validation of scaling laws and computational models, with particular emphasis given to the unsteady, separated, turbulent flow at the trailing edge. In addition, these experiments will provide fundamental insight into the fluid mechanics of trailing-edge noise generation in marine propulsion systems. This paper describes the experimental equipment and methods employed in the test program. Described herein is the use of the LCC's Laser Doppler Velocimetry (LDV) capability to acquire flow velocity mean and turbulence quantities, as well as estimates of boundary layer transition. Also presented is a Particle Imaging Velocimetry (PN) system developed for these experiments and employs seed injection upstream of the channel's flow straightener. Finally, a description is given of instrumentation mounted in the foil for measurement of vibration and surface static and dynamic pressures. [Significant assistance provided by personnel from NWSC-CD, Sponsored by Code 333 of the Office of Naval Research].
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Звіти організацій з теми "Particle Reynolds Number"

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Pullammanappallil, Pratap, Haim Kalman, and Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600038.bard.

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Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.
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