Rotational Motion of Large Particulate Doublets in Poiseuille Flow in a Capillary

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
E. J. McKeever ◽  
K. V. Sharp
Keyword(s):  
Shear Rate ◽  
Poiseuille Flow ◽  
Rotational Motion ◽  
Volume Concentration ◽  
Capillary Tube ◽  
Center Of Mass ◽  
Particle Diameter ◽  
Polystyrene Latex ◽  
Rotational Motions ◽  
Large Particulate

Doublets of 48-μm-diameter polystyrene latex particles are experimentally tracked in a Poiseuille flow in a capillary tube. The rotational motion of nine doublets is observed using video microscopy with a translating stage. The particle diameter to capillary diameter ratio is 0.17, volume concentration 0.5%, and Reynolds number approximately 0.5. The rotational motions of the “large” particulate doublets are compared with theory originally developed for doublets with particle-to-tube diameters of the order of 0.04; the doublet rotations in the present experiments agree reasonably well with the earlier theory when the shear rate for the large doublet is defined based on the location of the centroid of shear rather than the shear rate at the radial center of mass of the rotating doublet. Additionally, these doublets are readily classified as primary or secondary on the basis of the rotational period.

scholarly journals Determination of the Rate of Salt-Induced Rapid Coagulation of Polystyrene Latex Particles in Turbulent Flow Using Small Stirred Vessel

2018 ◽  
Vol 3 (1) ◽  
pp. 5
Author(s):  
Oktaviani Oktaviani ◽  
Yasuhisa Adachi
Keyword(s):  
Ad Hoc ◽  
Coupling Effect ◽  
Particle Diameter ◽  
Polystyrene Latex ◽  
Stirred Vessel ◽  
Colloidal Spheres ◽  
Rapid Coagulation ◽  
Mixing Intensity ◽  
Mixing Rates ◽  
Different Diameters

In our study, we revisited a previously reported method for evaluating the mixing intensity of uniform colloidal spheres in terms of their collision frequency, with the aim of evaluating the validity of this method in the case of a small stirred vessel equipped with an impeller with four paddles. The rates of the salt-induced rapid coagulation of polystyrene latex (PSL) particles with five different diameters were measured as functions of the rotation rate. The ad-hoc assumption of the linear additivity of the perikinetics and the orthokinetics of the coagulation process was used for the analysis. Our previously proposed equation for the rate of turbulent coagulation as a function of the particle diameter, determined for an end-over-end rotation mixing device, was confirmed to be valid. However, it was found that, for small particles and low-mixing rates, i.e., for low Peclet numbers, the rate of coagulation becomes larger than that predicted on the basis of linear additivity because of the coupling effect of Brownian motion and the fluid flow during turbulent mixing. This increase occurred even though the rate was lowered by the wall effect, which resulted in an inhomogeneous distribution of the mixing intensity.

Effect of Shear Surface Boundaries on Stress for Shearing Flow of Dry Metal Powders—An Experimental Study

1987 ◽  
Vol 109 (2) ◽  
pp. 232-237 ◽  
Author(s):  
K. Craig ◽  
R. H. Buckholz ◽  
G. Domoto
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Normal Stress ◽  
Particle Diameter ◽  
Surface Boundary ◽  
Metal Powders ◽  
Shear Surface ◽  
Shear Cell ◽  
Shearing Flow ◽  
Solids Content

This paper studies the rapid simple shearing flow of dry cohesionless metal powders contained between parallel rotating plates. In this study, an annular shear cell test apparatus was used; the dry metal powders are rapidly sheared by rotating one of the shear surfaces while the other shear surface remains fixed. Such a flow geometry is of interest to tribologists working in the area of dry or powder lubrication. The shear stress and normal stress on the stationary surface are measured as a function of the following parameters: shear surface boundary material and roughness, the shear-cell gap thickness, the shear-rate and the fractional solids content. Both the fractional solids content and the gap thickness are kept at prescribed values during stress measurements. In this experiment the metal powder tested is different from the shear transmission surface material; the effect on the measured normal and shear stress data are reported. The results show the dependence of the normal stress and the shear stress on the shear-rate, particle density and particle diameter. Likewise, a significant stress dependence on both the fractional solids content and the shear-cell gap thickness was observed.

Settling Behavior of Particles in Bubble Containing Newtonian Fluids: Experimental Study and Model Development

2021 ◽  
Author(s):  
Silin Jing ◽  
Xianzhi Song ◽  
Zhaopeng Zhu ◽  
Buwen Yu ◽  
Shiming Duan
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Volume Concentration ◽  
Settling Velocity ◽  
Particle Density ◽  
Particle Diameter ◽  
Newtonian Fluids ◽  
Spherical Particles ◽  
Bubble Volume ◽  
Particle Reynolds Number

Abstract Accurate description of cuttings slippage in the gas-liquid phase is of great significance for wellbore cleaning and the control accuracy of bottom hole pressure during MPD. In this study, the wellbore bubble flow environment was simulated by a constant pressure air pump and the transparent wellbore, and the settling characteristics of spherical particles under different gas volume concentrations were recorded and analyzed by highspeed photography. A total of 225 tests were conducted to analyze the influence of particle diameter (1–12mm), particle density (2700–7860kg/m^3), liquid viscosity and bubble volume concentration on particle settling velocity. Gas drag force is defined to quantitatively evaluate the bubble’s resistance to particle slippage. The relationship between bubble drag coefficient and particle Reynolds number is obtained by fitting the experimental results. An explicit settling velocity equation is established by introducing Archimedes number. This explicit equation with an average relative error of only 8.09% can directly predict the terminal settling velocity of the sphere in bubble containing Newtonian fluids. The models for predicting bubble drag coefficient and the terminal settling velocity are valid with particle Reynolds number ranging from 0.05 to 167 and bubble volume concentration ranging from 3.0% to 20.0%. Besides, a trial-and-error procedure and an illustrative example are presented to show how to calculate bubble drag coefficient and settling velocity in bubble containing fluids. The results of this study will provide the theoretical basis for wellbore cleaning and accurate downhole pressure to further improve the performance of MPD in treating gas influx.

scholarly journals Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

2013 ◽  
Vol 6 (3) ◽  
pp. 4123-4152 ◽  
Author(s):  
Y. Cai ◽  
J. R. Snider ◽  
P. Wechsler
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Scattered Light ◽  
Particle Diameter ◽  
Polystyrene Latex ◽  
Calibration Methods ◽  
Research Aircraft ◽  
Amplifier Gain ◽  
Gain Stage

Abstract. This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP). Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregate spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determination of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

Observations of rapidly flowing granular-fluid materials

1985 ◽  
Vol 150 ◽  
pp. 357-380 ◽  
Author(s):  
Daniel M. Hanes ◽  
Douglas L. Inman
Keyword(s):  
Shear Rate ◽  
Granular Material ◽  
Volume Concentration ◽  
Yield Criterion ◽  
Internal Boundary ◽  
Similar Data ◽  
Shear Rates ◽  
Lower Shear ◽  
High Shear Rates ◽  
Entire Flow

The rapid shearing of a mixture of cohesionless glass spheres and air or water was studied in an annular, parallel-plate shear cell designed after Savage (1978). Two types of flow were observed. In the first type of flow the entire mass of the granular material was mobilized. At high shear rates the shear and normal stresses were found to be quadratically dependent upon the mean shear rate (at constant volume concentration), in general agreement with the observations of Bagnold (1954) and Savage & Sayed (1984), and the ‘kinetic’ theory of Jenkins & Savage (1983). The stresses were found to be weakly dependent on the volume concentration up to approximately 0.5, and strongly dependent above this concentration. For flows in which water was the interstitial fluid, the ratio of the shear stress to the normal stress was slightly higher (than in air), and the stresses at lower shear rates were found to be more nearly linearly related to the shear rate. It is suggested that these effects are contributed to by the viscous dampening of grain motions by the water. The second type of flow was distinguished by the existence of an internal boundary above which the granular material deformed rapidly, but below which the granular material remained rigidly locked in place. The thickness of the shearing layer was measured to be between 5 and 15 grain diameters. The stress ratio at the bottom of the shearing layer was found to be nearly constant, suggesting the internal boundary is a consequence of the immersed weight of the shearing grains, and may be described by a Coulomb yield criterion. A scaled concentration is proposed to compare similar data obtained using different-sized materials or different apparatus. An intercomparison of the two types of flow studied, along with a comparison between the present experiments and those of Bagnold (1954) and Savage & Sayed (1984), suggests that the nature of the boundaries can have a significant effect upon the dynamics of the entire flow.

Modelization of dispersion of swimming bacteria in Poiseuille flow

2021 ◽  
Author(s):  
Akash Ganesh ◽  
Romain Rescanieres ◽  
Carine Douarche ◽  
Harold Auradou
Keyword(s):  
Shear Rate ◽  
Numerical Simulations ◽  
Poiseuille Flow ◽  
Dispersion Coefficient ◽  
Equations Of Motion ◽  
Critical Shear Rate ◽  
Uniform Shear ◽  
Simple Boundary ◽  
Swimming Bacteria ◽  
Local Shear

<p>We study the shear-induced migration of dilute suspensions of swimming bacteria (modelled as Active elongated Brownian Particles or ABPs) subject to plane Poiseuille flow in a confined channel. By incorporating very simple boundary conditions, we perform numerical simulations of the 3D equations of motion describing the change in position and orientation of the particles. We investigate the effects of confinement, of non-uniform shear and of aspect ratio of the particles on the overall dynamics of the ABPs population.</p><p>We particularly study the coupling between the local shear and the change in the orientation of the particles. We thus perform numerical simulations on both the case where the change in the orientation of the ABPs is purely diffusive (decoupled case) and the case where their orientation is coupled to the shear flow (coupled case). We observe that the decoupled case exhibits a Taylor dispersion <em>i.e.</em>  the effective dispersion coefficient of the ABPs along the direction of the flow is proportional to the square of the imposed shear at all shears. </p><p>However, for all the coupled cases we observe a transition from a Taylor to an active-Taylor regime at a critical shear rate, indicating the effect of shear coupling on the orientation dynamics of the particles. This critical shear rate is directly correlated to the degree of confinement. The change in the dispersion coefficient along the direction of the flow as function of the shear rate is in qualitative agreement with previous studies[1]. </p><p>To further understand these results, we also investigate the change in the dispersion coefficient in the other two directions along with the effect of the shape of the particles. We believe that this study should enhance our understanding of dispersion of bacteria through porous media, on surfaces etc. where shear flows are ubiquitous. </p><p>[1] Sandeep Chilukuri, Cynthia H.Collins, and Patrick T. Underhill. Dispersionof flagellated swimming microorganisms in planar poiseuille flow.Physics offluids, 27, (031902):1 –17, 2015</p>

PLATELET DEPOSITION ON ARTIFICIAL SURFACES: EFFECT OF PROTEIN PRECOATING, ENDOTHELIAL CELL COVERAGE AND SHEAR RATE

1987 ◽  
Author(s):  
A Poot ◽  
A Dekker ◽  
T Beugeling ◽  
A Bantjes ◽  
W G Van Aken
Keyword(s):  
Endothelial Cell ◽  
Shear Rate ◽  
Capillary Tube ◽  
Capillary Perfusion ◽  
Perfusate Flow ◽  
Platelet Deposition ◽  
Artificial Surface ◽  
Platelet Spreading ◽  
Von Willebrand

In the present study the in vitro capillary perfusion system according to Cazenave was used. This system consists of a capillary tube connected to a syringe containg the perfusate which consisted of washed human platalet (111 In-labeled or native) and washed red cells in Ca2+ /Mg2+ -containing Tyrode-albumin buffer. Perfusate flow is controlled by a syringe pump. Polyethylene tubes (PE, 0.75 mm ID, 25 cm long) were precoated with purified human von Willebrand factor (vWF), fibrinogen (Fb), fibronectin (Fn), immunoglobulin G (IgG), albumin (HSA) or plasma. Compared with uncoated PE, platelet deposition increased after precoating with vWF, Fb or Fn, and decreased by pre adsorbed IgG, HSA or plasma. Platelet deposition was positively correlated with shear rate only on surfaces precoated with vWF, Fb or Fn. Scanning electron microscopy showed platelet aggregates on IgG—coated PE, whereas on all other surfaces single adherent platelets were observed. Complete platelet spreading was only observed after precoating with Fn. In contrast with PE coated with vWF, Fb or Fn, platelet adhesion on uncoated PE did not increase further after 5 minutes of perfusion probably due to passivation of the surface by albumin present in the perfusate. This could be overcome by addition of Fb to the perfusate. Perfusates prepared in this way were used for studying the effect of human endothelial cell (HEC) coverage on platelet deposition. HEC were seeded at different densities in PE tubes precoated with partially purified Fn. Platelet deposition decreased with 2increasing HEC coverage, and was negligible at 60,000 HEC/cm . Our results indicate the applicability of this perfusion model for the in vitro testing of artificial surface thrombogenicity.

Perturbed rotational motions of a spheroid with cavity filled with a viscous fluid

2020 ◽  
pp. 095440622094154
Author(s):  
LD Akulenko ◽  
DD Leshchenko ◽  
KS Paly
Keyword(s):  
Reynolds Number ◽  
Viscous Fluid ◽  
Numerical Solution ◽  
Nonlinear Evolution ◽  
Center Of Mass ◽  
The Body ◽  
Angular Motion ◽  
Asymptotic Approach ◽  
Averaged Equations ◽  
Rotational Motions

We consider a motion about the center of mass of a spheroid with a cavity filled with a viscous fluid. It is assumed that the velocity of the fluid is sufficiently high, so the corresponding Reynolds number is small. The torque of forces acting on the body by the viscous fluid in the cavity is determined by the method developed in the works of F.L. Chernousko. Asymptotic approach permits to obtain some qualitative results and to describe nonlinear evolution of angular motion using simplified averaged equations and numerical solution.

Experiments on the lift and drag of spheres suspended in a Poiseuille flow

1964 ◽  
Vol 20 (3) ◽  
pp. 513-527 ◽  
Author(s):  
R. Eichhorn ◽  
S. Small
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Rotation Speed ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Dynamic Forces ◽  
Shear Parameter ◽  
Fluid Properties ◽  
Approach Velocity ◽  
Lift And Drag

An experimental investigation of the fluid dynamic forces on spheres suspended in a Poiseuille flow was performed. Small spheres of polystyrene, nylon, and Lucite, having diameters ranging from 0.061 in. to 0.126 in. were suspended in Poiseuille flows in a 0.419 in. diameter tube. Variations in particle size and density, the fluid properties, and the angle of inclination of the tube, resulted in a sphere Reynolds number (based on particle diameter and approach velocity) ranging from 80 to 250. The results are presented as curves which include the coefficients of lift and drag, and the dimensionless rotation speed plotted versus Reynolds number and a dimensionless shear parameter.

Sign in / Sign up

Export Citation Format

Share Document