Residual bubble volume formed behind a sphere plunging into liquid bath (meniscus breakdown with finite velocity of sphere penetration)

Standard Cryoprecipitate was prepared from fresh citrate phosphatedextrose plasma by snap freezing at —70° C and then thawing at +4° C in air for 18 hours. In 143 experiments the yield of Factor VIII from the starting plasma was 42%.In 64 paired experiments the Factor VIII yield in Cryoprecipitate from fresh plasma was increased, from 43% in the standard method to 56% when a quick thaw of 50 minutes at +4° C in a liquid bath was introduced. In 10 other paired experiments the yield in the standard method was raised from 51% to 61% when 90 minutes of super-cooling at —6° C in a liquid bath was introduced prior to snap freezing. When, however, the quick thaw and super-cooling modifications were combined in 42 paired experiments, the yield was only 49% compared with 42% by the standard method.It is concluded that this simple quick thaw modification will produce a greater yield of Factor VIII in Cryoprecipitate and that the addition of the technically more demanding super-cooling modification does not give a significantly greater yield.It seems likely that the longer period at +4° C in the standard method leads to denaturation of a proportion of the Factor VIII and loss of activity. Factor VIII antigen, however, was not lost. In a smaller number of experiments approximately all the Factor VIII was recovered in the Cryoprecipitate and its supernatant. Furthermore, the relative proportions of Factor VIII antigen and procoagulant in the Cryoprecipitate were found to vary in concert suggesting that the Factor VIII molecule is not dissociated in the process of cryoprecipitation.

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

10.1115/omae2021-62756 ◽

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.

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Thermoelectric-cooled liquid bath chiller capable of unattended operation at −28 °C

Review of Scientific Instruments ◽

10.1063/1.5063002 ◽

2018 ◽

Vol 89 (12) ◽

pp. 125101

Author(s):

Chad Lunceford ◽

Jeff Drucker

Keyword(s):

Liquid Bath

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Wave equations with finite velocity of propagation

Transactions of the American Mathematical Society ◽

10.1090/s0002-9947-1974-0330781-6 ◽

1974 ◽

Vol 188 ◽

pp. 127-127

Author(s):

Stephen J. Berman

Keyword(s):

Wave Equations ◽

Finite Velocity ◽

Velocity Of Propagation

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Analysis of the Motion and Deformation of a Bubble Rising in a Viscoelastic Fluid

Volume 2: Fora ◽

10.1115/fedsm2006-98363 ◽

2006 ◽

Author(s):

Shriram Pillapakkam ◽

Pushpendra Singh ◽

Denis L. Blackmore ◽

Nadine Aubry

Keyword(s):

Velocity Field ◽

Newtonian Fluid ◽

Viscoelastic Fluid ◽

Bubble Radius ◽

Polymer Concentration ◽

Deborah Number ◽

Two Phase ◽

Bubble Volume ◽

Recirculation Zones ◽

Bubble Rising

A finite element code based on the level set method is developed for performing two and three dimensional direct numerical simulations (DNS) of viscoelastic two-phase flow problems. The Oldroyd-B constitutive equation is used to model the viscoelastic liquid and both transient and steady state shapes of bubbles in viscoelastic buoyancy driven flows are studied. The influence of the governing dimensionless parameters, namely the Capillary number (Ca), the Deborah Number (De) and the polymer concentration parameter c, on the deformation of the bubble is also analyzed. Our simulations demonstrate that the rise velocity oscillates before reaching a steady value. The shape of the bubble, the magnitude of velocity overshoot and the amount of damping depend mainly on the parameter c and the bubble radius. Simulations also show that there is a critical bubble volume at which there is a sharp increase in the bubble terminal velocity as the increasing bubble volume increases, similar to the behavior observed in experiments. The structure of the wake of a bubble rising in a Newtonian fluid is strikingly different from that of a bubble rising in a viscoelastic fluid. In addition to the two recirculation zones at the equator of the bubble rising in a Newtonian fluid, two more recirculation zones exist in the wake of a bubble rising in viscoelastic fluids which influence the shape of a rising bubble. Interestingly, the direction of motion of the fluid a short distance below the trailing edge of a bubble rising in a viscoelastic fluid is in the opposite direction to the direction of the motion of the bubble, thus creating a “negative wake”. In this paper, the velocity field in the wake of the bubble, the effect of the parameters on the velocity field and their influence on the shape of the bubble are also investigated.

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