Fiber Orientation and Concentration Distribution in a Concentrated Suspension Flow Through a Complex Geometry

2003 ◽  
Author(s):  
Kazunori Yasuda ◽  
Noriyasu Mori
Keyword(s):  
Fiber Orientation ◽  
Complex Geometry ◽  
Flow Direction ◽  
Side Wall ◽  
Polymer Processing ◽  
Index Of Refraction ◽  
Fiber Concentration ◽  
Concentrated Suspension ◽  
Downstream Region ◽  
Flow Through

Distributions of fiber orientation and fiber concentration in slit flows of concentrated suspensions were measured. Slit channels were used in the experiments: a channel with an abrupt expansion and a crank geometry with six L-shaped corners. Such channels are usually used in a polymer processing. For visualization of fibers, an index-of-refraction matching method was employed, and tracer fibers having birefringence were suspended to observe between crossed polarizers. When fibers flow through an abrupt expansion, they rapidly orient in the direction perpendicular to the flow direction near the centerline. The fiber orientation, however, returns to the flow direction in the downstream region. In the L-shaped corner, fibers randomly orient because of the decelerating flow. In the downstream region of the L-shaped corner, fiber orientation is not symmetric with respect to the centerline. This seems to result from fiber-fiber interactions in the concentrated suspension. The fiber concentration is uniform over a width of a channel except adjacent to the side wall in the concentrated suspension, while it has a maximum apart from the side wall in the dilute suspension.

Finite Element Prediction of Multi-Size Particulate Flow Through Three-Dimensional Pump Casing

2015 ◽  
Author(s):  
Krishnan V. Pagalthivarthi ◽  
John M. Furlan ◽  
Robert J. Visintainer
Keyword(s):  
Finite Element ◽  
Field Data ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Side Wall ◽  
Secondary Flows ◽  
Low Flow ◽  
Particulate Flow ◽  
Main Stream ◽  
Flow Through

Flow through centrifugal pump casing is highly complex in nature due to the complex geometry of the casing. While simplified two dimensional modeling of pump casing reveals the overall flow pattern and pressure distribution, a complete 3D model of pump casing is essential to fully capture the interaction of the primary main stream flow and the secondary flows especially in areas of heavy recirculation. This paper presents steady state finite element simulation of multi-size particulate slurry flow through three dimensional pump casing. The flow field and concentration distribution is presented for different cross-sectional planes. The multi-size particulate flow simulation results are compared with two mono-size particle simulations using (1) the concentration weighted mean diameter of the slurry and (b) the D50 size of the slurry. Qualitative comparison is made with the wear rate predicted by the simulations and the field data. Simulations and field data show that at low flow rates, the side-wall gouging wear near the tongue region becomes significant.

Flow of Polymeric Liquid in Complex Geometry

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Cross Section ◽  
Complex Geometry ◽  
Rectangular Channel ◽  
Polymer Processing ◽  
Polymeric Liquid ◽  
Cross Sectional ◽  
Polymeric Liquids ◽  
Flow Through ◽  
Newtonian Liquids ◽  
Sectional Shape

The flow geometry encountered in many polymer processing operations of industrial importance is often far more complex than that in cylindrical or slit dies. As will be shown in the following chapters, the industry manufactures polymeric products using very complex flow geometries. For instance, the fiber industry produces “shaped fibers,” which have cross sections that are noncircular. What is most intriguing in the production of shaped fibers is that a desired fiber shape is often produced by spinneret holes whose cross-sectional shape is quite different from that of the final fiber produced. Hence, an important question may be raised as to how one can determine, from a sound theoretical basis, the cross-sectional shape of spinneret holes that will produce a fiber with a desired cross-sectional shape. In extrusion and injection molding, a polymeric liquid invariably passes through a large cross section before entering into a small cross section, and such a flow is referred to as “entrance flow.” The entrance flow of polymeric liquids, due to their viscoelastic nature, is quite different from that of Newtonian liquids. Similarly, the flow behavior of viscoelastic polymeric liquids near the exit of a die, commonly referred to as “exit flow,” is quite different from that of Newtonian liquids. A better understanding of the unique characteristics of both entrance and exit flows of viscoelastic polymeric fluids is essential for successful design of extrusion dies and molds, as well as to solve difficult technical problems related to a particular processing operation. Before presenting specific polymer processing operations in following chapters, in this chapter we consider the flow of polymeric liquids through complex geometry: (1) fully developed flow through a rectangular channel with uniform channel depth; (2) fully developed flow through a rectangular channel with a moving channel wall; (3) flow through a rectangular channel with varying channel depth; (4) flow in the entrance region of a rectangular die having constant cross section; (5) flow through a tapered die; (6) flow in the exit region of a cylindrical or slit die; (7) flow through a slit die having side holes; and (8) flow through a coat-hanger die.

scholarly journals Fibers Effects on Contract Turbulence Using a Coupling Euler Model

2021 ◽  
Vol 11 (15) ◽  
pp. 7126
Author(s):  
Wei Yang ◽  
Pei Hu
Keyword(s):  
Boundary Layer ◽  
Velocity Profile ◽  
Fiber Orientation ◽  
Bottom Layer ◽  
Orientation Distribution ◽  
Industrial Applications ◽  
Dynamics Simulation ◽  
Fiber Concentration ◽  
Fibers Orientation ◽  
Process Strategy

Fiber additive will induce the rheological behavior of suspension, resulting in variation in velocity profile and fiber orientation especially for the non-dilute case. Based on the fluid-solid coupling dynamics simulation, it shows that the fiber orientation aligns along the streamline more and more quickly in the central turbulent region as the fiber concentration increases, especially contract ratio Cx > 4. However, fibers tend to maintain the original uniform orientation and are rarely affected by the contract ratio in the boundary layer. The fibers orientation in the near semi-dilute phase is lower than that in the dilute phase near the outlet, which may be the result of the hydrodynamic contact lubrication between fibers. The orientation distribution and concentration of the fibers change the viscous flow mechanism of the suspension microscopically, which makes a velocity profile vary with the phase concentration. The velocity profile of the approaching semi-dilute phase sublayer is higher than that of the dilute and semi-dilute phases on the central streamline and in the viscous bottom layer, showing weak drag reduction while the situation is opposite on the logarithmic layer of the boundary layer. The relevant research can provide a process strategy for fiber orientation optimization and rheological control in the industrial applications of suspension.

scholarly journals Assessment of Mercury-Polluted Soils Adjacent to an Old Mercury-Fulminate Production Plant

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
M. Camps Arbestain ◽  
L. Rodríguez-Lado ◽  
M. Bao ◽  
F. Macías
Keyword(s):  
Surface Waters ◽  
Contaminated Soils ◽  
Flow Direction ◽  
Surface Flow ◽  
Mercury Contamination ◽  
Production Plant ◽  
Polluted Soils ◽  
Flow Through ◽  
Contamination Of Soils ◽  
Surrounding Soil

Mercury contamination of soils and vegetation close to an abandoned Hg-fulminate production plant was investigated. Maximum concentrations of Hg (>6.5 gkg−1soil) were found in the soils located in the area where the wastewater produced during the washing procedures carried out at the production plant used to be discharged. A few meters away from the discharge area, Hg concentrations decreased to levels ranging between 1 and 5 gkg−1, whereas about 0.5 ha of the surrounding soil to the NE (following the dominant surface flow direction) contained between 0.1 and 1 gkg−1. Mercury contamination of soils was attributed (in addition to spills from Hg containers) to (i) Hg volatilization with subsequent condensation in cooler areas of the production plant and in the surrounding forest stands, and (ii) movement of water either by lateral subsurface flow through the contaminated soils or by heavy runoff to surface waters.

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