Towards unified drag laws for inertial flow through fibrous materials

2012 ◽  
Vol 207-208 ◽  
pp. 35-48 ◽  
Author(s):  
K. Yazdchi ◽  
S. Luding
Keyword(s):  
Fibrous Materials ◽  
Inertial Flow ◽  
Flow Through ◽  
Drag Laws

Impregnation of Fibrous Materials with Lc Polyesters and Blends on Their Base

2000 ◽  
Vol 10 (2) ◽  
pp. 62-72 ◽  
Author(s):  
S. V. Kotomin ◽  
S. V. Antonov ◽  
V. E. Dreval ◽  
M. L. Kerber ◽  
V. G. Kulichikhin
Keyword(s):  
Shear Rate ◽  
Rheological Characteristics ◽  
Fibrous Materials ◽  
Impregnation Process ◽  
Initial Stage ◽  
Viscosity Increase ◽  
Flow Through ◽  
Impregnation Condition ◽  
Capillary Walls ◽  
Low Shear

Abstract Impregnation and infiltration of fibrous materials by LC copolyester melts and the blends with viscous thermo-plastic polysulphone were quantitatively described as unsteady and steady stages in terms of rheological characteristics of the melts using an equivalent capillary model. Addition of LC polyester to viscous thermoplastic melt noticeably enhances impregnation condition. Study of the melt flow through various capillaries demonstrated a development of the melt slippage at high shear rate along the capillary walls. Slippage phenomena may be important at the initial stage of impregnation but can be neglected for final stage due to low shear rate in the last case. On the other hand, at those conditions a yield stress of the melt may considerably complicate the impregnation process due to a drastic viscosity increase.

scholarly journals On the Transition From Creeping to Inertial Flow in Arrays of Cylinders

2010 ◽  
Author(s):  
K. Yazdchi ◽  
S. Srivastava ◽  
S. Luding
Keyword(s):  
Porous Media ◽  
Darcy’S Law ◽  
Computational Study ◽  
Darcy's Law ◽  
Natural Processes ◽  
Inertial Flow ◽  
Flow Through ◽  
High Reynolds ◽  
An Array Of Cylinders ◽  
Element Method

Many important natural processes involving flow through porous media are characterized by large filtration velocity. Therefore, it is important to know when the transition from viscous to the inertial flow regime actually occurs in order to obtain accurate models for these processes. In this paper, a detailed computational study of laminar and inertial, incompressible, Newtonian fluid flow across an array of cylinders is presented. Due to the non-linear contribution of inertia to the transport of momentum at the pore scale, we observe a typical departure from Darcy’s law at sufficiently high Reynolds number (Re). Our numerical results show that the weak inertia correction to Darcy’s law is not a square or a cubic term in velocity, as it is in the Forchheimer equation. Best fitted functions for the macroscopic properties of porous media in terms of microstructure and porosity are derived and comparisons are made to the Ergun and Forchheimer relations to examine their relevance in the given porosity and Re range. The results from this study can be used for verification and validation of more advanced models for particle fluid interaction and for the coupling of the discrete element method (DEM) with finite element method (FEM).

scholarly journals The Viscous and Inertial Flow of Air through Perforated Papers

1989 ◽  
Vol 14 (5) ◽  
pp. 253-260
Author(s):  
RR Baker
Keyword(s):  
Viscous Flow ◽  
Gas Flow ◽  
Air Flow ◽  
Total Flow ◽  
Cellulose Fibres ◽  
Perforation Hole ◽  
Paper Making ◽  
Inertial Flow ◽  
Flow Through ◽  
Cigarette Paper

AbstractInherently porous cigarette paper consists of an interlocking network of cellulose fibres interspersed with chalk particles. Spaces in this matrix are of the order of 1 AAµm wide which is small compared to the paper thickness (usually 20 AAµm to 40 AAµm). However, when cigarette paper is perforated after the paper-making process, e.g. by an electrostatic or mechanical process, the perforation holes are relatively large, usually having mean diameters of the same order of magnitude as the paper thickness. The total flow of air through perforated cigarette paper thus consists of two components: viscous flow through the porous structure of the paper inherent from the paper-making process, and inertial flow through the perforation holes. Since the air flow / pressure relationships due to these two components of flow differ and since the two components are additive, the total flow through perforated paper may be expressed as: Q = Z A P + Z’ A Pn, where Q is the air flow (cm3 min-1), A is the area of paper (cm2) exposed to the flowing air, P is the pressure difference across the paper (kilopascal), Z is the base permeability of the paper due to viscous flow through the spaces inherent from the paper-making process (cm min-1 kPa-1 or Coresta unit), Z’ is the permeability of the paper due to inertial flow through the perforation holes (cm min-1 kPa-1/n) and n is a constant for a given set of perforation holes. This equation adequately describes gas flow through a variety of perforated cigarette and tipping papers. By using different gases, it is confirmed that Z depends on viscous forces and Z’ depends on inertial forces. By examining the flow of air through a large number of papers with perforation holes of different sizes, it is shown that Z’ is dependent on the total area of perforation holes, and that a jet-contraction effect occurs as the air travels through the paper. The parameter n is shown to have a value between 0.5 and 1.0, and this value is related to mean perforation-hole size. The permeability of cigarette paper is defined as the flow of air through the paper when the pressure across the paper is 1 kilopascal. Thus from the above equation the “total permeability” of perforated cigarette paper is equal to Z + Z'.

A microscopic study of MHD fractional inertial flow through Forchheimer medium

2017 ◽  
Vol 55 (4) ◽  
pp. 1690-1703 ◽  
Author(s):  
Muhammad Shoaib Anwar ◽  
Amer Rasheed
Keyword(s):  
Microscopic Study ◽  
Inertial Flow ◽  
Flow Through

Modeling of Differential Pressure Buildup during Flow through Beds of Fibrous Materials

2006 ◽  
Vol 29 (8) ◽  
pp. 997-1000 ◽  
Author(s):  
A. Grahn ◽  
E. Krepper ◽  
S. Alt ◽  
W. Kästner
Keyword(s):  
Differential Pressure ◽  
Fibrous Materials ◽  
Pressure Buildup ◽  
Flow Through

Effect of Dynamic Surface Tension on Foam Flow Through Fibrous Materials

1991 ◽  
Vol 61 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Douglas E. Hirt ◽  
Robert K. Prud'homme ◽  
Ludwig Rebenfeld
Keyword(s):  
Surface Tension ◽  
Dynamic Surface Tension ◽  
Fibrous Materials ◽  
Dynamic Surface ◽  
Foam Flow ◽  
Flow Through

Development of apical pits in chloride cells of the gills of Pimephales promelas after chronic exposure to acid water

1983 ◽  
Vol 41 ◽  
pp. 462-463
Author(s):  
Richard L. Leino ◽  
Jon G. Anderson ◽  
J. Howard McCormick
Keyword(s):  
Confidence Interval ◽  
Chronic Exposure ◽  
Lake Superior ◽  
Pimephales Promelas ◽  
Chloride Cells ◽  
Fathead Minnows ◽  
Secondary Lamellae ◽  
Untreated Water ◽  
Water Ph ◽  
Flow Through

Groups of 12 fathead minnows were exposed for 129 days to Lake Superior water acidified (pH 5.0, 5.5, 6.0 or 6.5) with reagent grade H2SO4 by means of a multichannel toxicant system for flow-through bioassays. Untreated water (pH 7.5) had the following properties: hardness 45.3 ± 0.3 (95% confidence interval) mg/1 as CaCO3; alkalinity 42.6 ± 0.2 mg/1; Cl- 0.03 meq/1; Na+ 0.05 meq/1; K+ 0.01 meq/1; Ca2+ 0.68 meq/1; Mg2+ 0.26 meq/1; dissolved O2 5.8 ± 0.3 mg/1; free CO2 3.2 ± 0.4 mg/1; T= 24.3 ± 0.1°C. The 1st, 2nd and 3rd gills were subsequently processed for LM (methacrylate), TEM and SEM respectively.Three changes involving chloride cells were correlated with increasing acidity: 1) the appearance of apical pits (figs. 2,5 as compared to figs. 1, 3,4) in chloride cells (about 22% of the chloride cells had pits at pH 5.0); 2) increases in their numbers and 3) increases in the % of these cells in the epithelium of the secondary lamellae.

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