scholarly journals Correction to: Dewatering of foam-laid and water-laid structures and the formed web properties

Cellulose ◽  
2019 ◽  
Vol 27 (3) ◽  
pp. 1147-1147
Author(s):  
Jani Lehmonen ◽  
Elias Retulainen ◽  
Jouni Paltakari ◽  
Karita Kinnunen-Raudaskoski ◽  
Antti Koponen
Keyword(s):  
Apparent Viscosity ◽  
Bubble Radius ◽  
Original Publication ◽  
Tube Radius ◽  
Capillary Tubes ◽  
Air Content

In the original publication of the article, the sentences “Hirasaki and Lawson (1985) found a decrease by almost a factor of 104 occurring in the apparent viscosity of foam (air content 83%) in capillary tubes as the ratio of bubble radius to tube radius, , increased from 0.1 to 10.

Physical basis of the dependence of blood viscosity on tube radius

1960 ◽  
Vol 198 (6) ◽  
pp. 1193-1200 ◽  
Author(s):  
Robert H. Haynes
Keyword(s):  
Flow Rate ◽  
Blood Viscosity ◽  
Apparent Viscosity ◽  
Hind Limb ◽  
Marginal Zone ◽  
Tube Wall ◽  
Effective Diameter ◽  
Tube Radius ◽  
Vascular Bed ◽  
A Cell

Two theories are applied to measurements of the decrease in apparent viscosity of blood in narrow tubes (Fahraeus-Lindqvist effect). First, the effect may be attributed to the presence of unsheared laminae in the fluid (sigma phenomenon), and it was found that the thickness of such laminae must vary between 3.5 µ at 10% hematocrit and 34 µ at 80%. Alternatively, the effect may be caused by a cell-free marginal zone adjacent to the tube wall, which would have to be 6 µ thick at 10% hematocrit and 1.5 µ at 80%. There is a slight suggestion in the data that the effect may be reversed as the flow rate approaches zero (i.e. the apparent viscosity rises in small tubes). Finally, a method is proposed for calculating the effective diameter of a vascular bed, and it was found to be 55 µ for a dog's hind limb.

Motion of an array of drops through a cylindrical tube

1998 ◽  
Vol 358 ◽  
pp. 1-28 ◽  
Author(s):  
C. COULLIETTE ◽  
C. POZRIKIDIS
Keyword(s):  
Stokes Flow ◽  
Apparent Viscosity ◽  
Numerical Solutions ◽  
Initial Period ◽  
Mathematical Formulation ◽  
Axisymmetric Flow ◽  
Circular Cross Section ◽  
Cylindrical Tube ◽  
Boundary Integral ◽  
Tube Radius

We study the pressure-driven transient motion of a periodic file of deformable liquid drops through a cylindrical tube with circular cross-section, at vanishing Reynolds number. The investigations are based on numerical solutions of the equations of Stokes flow obtained by the boundary-integral method. It is assumed that the viscosity and density of the drops are equal to those of the suspending fluid, and the interfaces have constant tension. The mathematical formulation uses the periodic Green's function of the equations of Stokes flow in a domain that is bounded externally by a cylindrical tube, which is computed by tabulation and interpolation. The surface of each drop is discretized into quadratic triangular elements that form an unstructured interfacial grid, and the tangential velocity of the grid-points is adjusted so that the mesh remains regular for an extended but limited period of time. The results illustrate the nature of drop motion and deformation, and thereby extend previous studies for axisymmetric flow and small-drop small-deformation theories. It is found that when the capillary number is sufficiently small, the drops start deforming from a spherical shape, and then reach slowly evolving quasi-steady shapes. In all cases, the drops migrate radially toward the centreline after an initial period of rapid deformation. The apparent viscosity of the periodic suspension is expressed in terms of the effective pressure gradient necessary to drive the flow at constant flow rate. For a fixed period of separation, the apparent viscosity of a non-axisymmetric file is found to be higher than that of an axisymmetric file. In the case of non-axisymmetric motion, the apparent viscosity reaches a minimum at a certain ratio of the drop separation to tube radius. Drops with large effective radii to tube radius ratios develop slipper shapes, similar to those assumed by red blood cells in flow through capillaries, but only for capillary numbers in excess of a critical value.

Using a classic paper by Robin Fåhraeus and Torsten Lindqvist to teach basic hemorheology

2013 ◽  
Vol 37 (2) ◽  
pp. 129-133 ◽  
Author(s):  
Linea Natalie Toksvang ◽  
Ronan M. G. Berg
Keyword(s):  
Apparent Viscosity ◽  
Peripheral Resistance ◽  
Tissue Perfusion ◽  
Vessel Diameter ◽  
Glass Capillary ◽  
Capillary Tubes ◽  
Cell Deformability ◽  
Blood Flows ◽  
Classic Paper

“The viscosity of the blood in narrow capillary tubes” by Robin Fåhraeus and Torsten Lindqvist ( Am J Physiol 96: 562–568, 1931) can be a valuable opportunity for teaching basic hemorheological principles in undergraduate cardiovascular physiology. This classic paper demonstrates that a progressive decline in apparent viscosity occurs when blood flows through glass capillary tubes of diminishing radius, which was later designated as the “Fåhraeus-Lindqvist effect.” Subsequent studies have shown that apparent viscosity continues to decline at diameters that correspond to the arteriolar segments of the systemic vascular tree, where the majority of the total peripheral resistance resides and is actively regulated in vivo. The Fåhraeus-Lindqvist effect thus reduces microvascular resistance, thereby maintaining local tissue perfusion at a relatively lower blood pressure. The paper by Fåhraeus and Lindqvist can be used as a platform for a plenary discussion of these concepts as well as of the relationships among hematocrit, vessel diameter, red blood cell deformability, and resistance to blood flow and how these factors may affect the work of the heart.

The Use of Capillary Tube Networks in Reservoir Performance Studies: II. Effect of Heterogeneity and Mobility on Miscible Displacement Efficiency

1972 ◽  
Vol 12 (04) ◽  
pp. 345-351 ◽  
Author(s):  
Ralph Simon ◽  
F.J. Kelsey
Keyword(s):  
Porous Media ◽  
Plug Flow ◽  
Network Models ◽  
Miscible Displacement ◽  
Mobility Ratio ◽  
Displacement Efficiency ◽  
Tube Radius ◽  
Capillary Tubes ◽  
Miscible Displacements ◽  
Equal Density

Abstract Part II of this series extends the network technique to all miscible displacement mobility ratios and introduces a heterogeneity factor called H. As a result, the network model can be used to study the general miscible displacement case, i.e., miscible displacements with all mobility ratios in linear or areal flow systems having a range of heterogeneities. Engineering charts are presented which show the relationship between recovery, mobility ratio, heterogeneity and pore volumes injected. Introduction Part I of this series dealt with equal viscosity, and equal-density miscible displacements. Part II extends the network technique to miscible displacements with all mobility ratios. Part II also introduces a heterogeneity factor, H, used in designing network models. The equal-density limitation is retained. Plug flow is assumed in the capillary tubes. The Plug flow is assumed in the capillary tubes. The original fluid and injected fluid are considered ideal so there are no heat or volumetric effects from mixing. Viscosity of the mixtures is discussed in the section on Calculations. Part II is divided into three main sections. The first discusses the calculation methods. The second shows comparisons of data calculated by the network technique and data measured for real porous media. These comparisons demonstrate that porous media. These comparisons demonstrate that network models can indeed be used to predict the performance of displacements in real porous media. performance of displacements in real porous media. The third section illustrates the application of network methods to reservoir engineering problems. The illustration is accomplished with a series of charts that relate oil recovery to heterogeneity, mobility ratio, and pore volumes injected for the special cases of a linear system (length/width = 3/1) and five-spots. CALCULATIONS Two primary steps are required to calculate the effect of heterogeneity and mobility on miscible displacement efficiency. The first is to design a network with the desired heterogeneity. The second is to calculate the displacement phenomena that occur as the injection fluid advances through the network. A network is designed by specifying the following:Type linear or areal flow models.Tube configuration diamond, hexagonal, etc. In this paper all networks are the diamond configurations shown in Fig. 1.Size number of tubes in the network.Heterogeneity by using the heterogeneity factor (see Fig 2a).Tube radius distribution function all tube radius distribution functions are the single modal type shown in Fig. 2a.Tube location distribution all location distributions are random. SPEJ P. 345

scholarly journals The Rate of Growth of Vapor Bubbles in Superheated Water

1953 ◽  
Vol 20 (4) ◽  
pp. 537-545
Author(s):  
Paul Dergarabedian
Keyword(s):  
Bubble Radius ◽  
Equation Of Motion ◽  
Heat Diffusion ◽  
Air Bubbles ◽  
Finite Range ◽  
Superheated Water ◽  
Vapor Bubbles ◽  
Bubble Wall ◽  
Air Content ◽  
Rate Of Growth

Abstract Calculations are presented for the dynamic stability of vapor and air bubbles in superheated water. These calculations indicate that the values of the bubble radii for which the equilibrium is unstable are restricted to a finite range of radii whose values are governed by the temperature of the water and the initial air content in the bubble. Two theoretical solutions for the rate of growth of these unstable bubbles are considered: (a) Solution of the equation of motion of the bubble radius with the assumption that there is no heat diffusion across the bubble wall; (b) solution which includes the effect of heat diffusion. The two solutions differ appreciably. These two solutions are then compared with the experimental data on the growth of the vapor bubbles in superheated water. This comparison shows agreement with the solution with the effect of heat diffusion included.

scholarly journals Impacts of Low Atmospheric Pressure on Properties of Cement Concrete in Plateau Areas: A Literature Review

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1384 ◽  
Author(s):  
Jinyang Huo ◽  
Zhenjun Wang ◽  
Huaxin Chen ◽  
Rui He
Keyword(s):  
Atmospheric Pressure ◽  
Bubble Radius ◽  
Hardened Cement ◽  
Nano Silica ◽  
Cement Concrete ◽  
Air Content ◽  
Normal Atmospheric Pressure ◽  
New Type ◽  
Low Atmospheric Pressure ◽  
Bubble Characteristics

Low atmospheric pressure (LAP) can enormously affect properties of cement concrete in plateau areas. There are fewer studies and attendances on this issue than those of cement concrete in normal atmospheric pressure (AP), because of the limitations of both environmental conditions and instruments. In order to improve properties of cement concrete under LAP, influences of LAP on properties of cement concrete were reviewed in this work. The influence rules and mechanism on properties of cement concrete were summarized. The corresponding mechanism and techniques were put forward for enhancing the properties of cement concrete. The results of researchers show that LAP can significantly reduce the air entraining ability of the air entraining agent (AEA). Air content in concrete linearly decreases with the decrease of AP when other conditions are constant. If the initial air content is high, the decrease rate of air content increases with the decrease of AP. When the initial air content in cement concretes is similar, the greater the slump of cement concrete, the stronger its resistance to the decrease of air content caused by the decrease of AP. In addition, the condition of the bubble characteristics of hardened cement concrete under LAP is worse than that under normal AP. Therefore, the change of concrete properties under LAP is mainly attributed to these bubble characteristics, such as air content, bubble spacing coefficient, bubble radius and bubble specific surface area. In this work, nano-silica (negative charges) with cationic oligomeric surfactants is recommended as a new type of AEA to optimize the bubble characteristics under LAP in plateau areas.

Producing Quality Peanut Seed

EDIS ◽  
1969 ◽  
Vol 2002 (8) ◽  
Author(s):  
Elmo B. Whitty
Keyword(s):  
Cooperative Extension ◽  
Cooperative Extension Service ◽  
Extension Service ◽  
Publication Date ◽  
Original Publication ◽  
Peanut Seed ◽  
University Of Florida ◽  
Agricultural Sciences

This document is SS-AGR-187, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November 2002.

Citrus Blemishes and Decay Caused by Fungi and Bacteria

EDIS ◽  
2017 ◽  
Vol 2017 (3) ◽  
Author(s):  
Mark A. Ritenour ◽  
Jamie D. Burrow ◽  
Megan M Dewdney ◽  
John Zhang
Keyword(s):  
Publication Date ◽  
Original Publication ◽  
Fruit Decay ◽  
Florida Citrus ◽  
Identification Tool

This is a quick identification tool of citrus blemishes and fruit decay caused by fungi and bacteria in Florida citrus. Original publication date May 2017. 

Wheel Bug, Arilus cristatus (Linnaeus) (Insecta: Hemiptera: Reduviidae)

EDIS ◽  
2017 ◽  
Vol 2017 (2) ◽  
pp. 5
Author(s):  
F. W. Mead
Keyword(s):  
Life History ◽  
Publication Date ◽  
Original Publication ◽  
Medical Importance

Contents: Introduction - Synonymy - Distribution - Description and Identification - Life History - Notes on Behavior - Importance as a Predator - Medical Importance - Enemies - Selected References This document is EENY086, one of a series of the Department of Entomology and Nematology, UF/IFAS Extension. Original publication date June 1999. Revised December 2005, August 2014, and March 2017. Visit the EDIS website at http://edis.ifas.ufl.edu. This document is also available on the Featured Creatures website at http://entnemdept.ifas.ufl.edu/creatures/.

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