Predictability of apparent viscosity in a vibratory shearing flow field

2009 ◽  
Vol 113 (3) ◽  
pp. 1560-1565 ◽  
Author(s):  
Jin-Ping Qu ◽  
Bao-Hua Wei ◽  
Zhi-Tao Yang ◽  
Yong-Hong Cai
Keyword(s):  
Flow Field ◽  
Apparent Viscosity ◽  
Shearing Flow

THE CONCOMITANT-EFFECT OF ELECTRORHEOLOGICAL FLUID IN A CONTROL FLOW FIELD

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1263-1269 ◽  
Author(s):  
Shi-sha ZHU ◽  
Toyohisa FUJITA ◽  
Qi-xin WANG ◽  
Kejun LIU ◽  
Gjergj DODBIBA
Keyword(s):  
Flow Field ◽  
Power Transmission ◽  
Electrorheological Fluid ◽  
Control Flow ◽  
Fluid Power ◽  
Control Technology ◽  
Capture Effect ◽  
Shearing Flow ◽  
Er Fluid ◽  
Research Show

The description of ER response in a flow field is a key issue in researching control technology of ER fluid. In this paper, an experimental work on controlling flow field in fluid power transmission has been carried out. The results of research show that the control flow field differs from the rotary shearing flow field in an experimental instrument. Besides the ER effect there is a concomitant-effect of ER response called "capture effect" in the field, which is unbeneficial to the control on fluid power transmission.

Non-Newtonian effects in steady motion of some idealized elastico-viscous liquids

1958 ◽  
Vol 245 (1241) ◽  
pp. 278-297 ◽  
Keyword(s):  
Steady Flow ◽  
Apparent Viscosity ◽  
Steady Motion ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Straight Pipe ◽  
Shearing Flow ◽  
Viscous Liquids ◽  
Variable Shear ◽  
Steady Shearing

Normal-stress effects and the variation of apparent viscosity with rate of shear in simple types of steady flow of certain idealized elastico-viscous liquids are discussed. The liquids are those whose behaviour at sufficiently small variable shear stresses can be characterized by three constants (a coefficient of viscosity, a relaxation time and a retardation time) and whose invariant differential equations of state for general motion (involving eight independent physical constants) are linear in the stresses and include terms of no higher degree than the second in the stresses and velocity gradients together. The normal stresses which, in addition to shear stresses, are present in such a liquid in a state of simple shearing flow, or in flow in a circular pipe, or between rotating cylinders, are investigated; and the conditions under which the Weissenberg climbing effect will occur, in a positive or negative sense, are examined. In many liquids of this class, steady rectilinear flow under a uniform pressure gradient is not always possible in a straight pipe of arbitrary section, nor is steady flow in horizontal circles in a region bounded by arbitrary surfaces of revolution in relative rotation about common vertical axis. The behaviour of these idealized liquids when sheared in a narrow gap between a rotating wide-angled cone and a flat plate is compared with the observations of Roberts (1952, 1953) on some real elastico-viscous liquids. Certain liquids of this class, characterized by six independent constants satisfying certain inequalities, exhibit rheological behaviour which is, at least qualitatively, similar to the behaviour of many real elastico-viscous liquids in the following respects: the behaviour at small variable shear stresses, the variation of apparent viscosity with rate of steady shearing, the climbing effect up a vertical rod rotated in the liquid, and a distribution of normal stresses equivalent to an extra tension along the streamlines (with an isotropic state of stress in the plane normal to the streamlines) which is present in all the simple types of steady shearing flow investigated. These liquids can flow steadily in straight lines through a straight pipe of any section.

A comparison of thermal degradation kinetic mechanisms between elongational and shearing flow fields for nano-silica/IFR synergistic fire retardant polypropylene nanocomposites

2019 ◽  
Vol 9 (9) ◽  
pp. 1033-1042 ◽  
Author(s):  
Zheng-Huan Wu ◽  
Jun-Xin Guo ◽  
Qi-Xiang Fan ◽  
Quan Wang ◽  
Yu-Jun Cai ◽  
...  
Keyword(s):  
Flow Field ◽  
Fire Retardant ◽  
Elongational Flow ◽  
Nano Silica ◽  
Ozawa Method ◽  
Screw Extruder ◽  
Degradation Kinetic ◽  
Shearing Flow ◽  
Polypropylene Nanocomposites ◽  
Kinetic Mechanisms

In this work, the same formulations of Nano-Silica/intumescent fire retardant polypropylene nanocomposites were prepared via a novel vane extruder and a tri-screw extruder, which represented elongational flow field and shearing flow field, respectively. Not only the synergistic combustion mechanisms of Kissinger method and Flynn-Wall-Ozawa method were revealed, but also the combustion effect and efficiency were compared. Both two methods proved specimens that processed by TE exhibited higher thermal stability. The smaller aggregates of physical initial Nano-Silica, the better dispersivity of aggregates in specimens that processed by VE. Such property broke the compactness degree of char layer.

The rheology of a semi-dilute suspension of swimming model micro-organisms

2007 ◽  
Vol 588 ◽  
pp. 399-435 ◽  
Author(s):  
TAKUJI ISHIKAWA ◽  
T. J. PEDLEY
Keyword(s):  
Shear Flow ◽  
Flow Field ◽  
Simple Shear ◽  
Apparent Viscosity ◽  
The Other ◽  
Surface Velocity ◽  
Simple Shear Flow ◽  
Other Hand ◽  
Dilute Suspension ◽  
Micro Organisms

The rheological properties of a cell suspension may play an important role in the flow field generated by populations of swimming micro-organisms (e.g. in bioconvection). In this paper, a swimming micro-organism is modelled as a squirming sphere with prescribed tangential surface velocity, in which the centre of mass of the sphere may be displaced from the geometric centre (bottom-heaviness). Effects of inertia and Brownian motion are neglected, because real micro-organisms swim at very low Reynolds numbers but are too large for Brownian effects to be important. The three-dimensional movement of 64 identical squirmers in a simple shear flow field, contained in a cube with periodic boundary conditions, is dynamically computed, for random initial positions and orientations. The computation utilizes a database of pairwise interactions that has been constructed by the boundary element method. The restriction to pairwise additivity of forces is expected to be justified if the suspension is semi-dilute. The results for non-bottom-heavy squirmers show that the squirming does not have a direct influence on the apparent viscosity. However, it does change the probability density in configuration space, and thereby causes a slight decrease in the apparent viscosity atO(c2), wherecis the volume fraction of spheres. In the case of bottom-heavy squirmers, on the other hand, the stresslet generated by the squirming motion directly contributes to the bulk stress atO(c), and the suspension shows strong non-Newtonian properties. When the background simple shear flow is directed vertically, the apparent viscosity of the semi-dilute suspension of bottom-heavy squirmers becomes smaller than that of inert spheres. When the shear flow is horizontal and varies with the vertical coordinate, on the other hand, the apparent viscosity becomes larger than that of inert spheres. In addition, significant normal stress differences appear for all relative orientations of gravity and the shear flow, in the case of bottom-heavy squirmers.

Modelling of Flow Behaviour and Rheological Properties of M2 Steel in Semisolid State

2021 ◽  
Vol 903 ◽  
pp. 73-78
Author(s):  
Sudip Simlandi ◽  
Nilkanta Barman
Keyword(s):  
Shear Rate ◽  
Flow Field ◽  
Apparent Viscosity ◽  
Step Change ◽  
Time Dependent ◽  
Transient Condition ◽  
Structural Parameter ◽  
Parallel Plates ◽  
Semisolid State ◽  
Wide Range

The present study develops a model to investigate time dependent behaviours of M2 steel in semisolid state during step-change in shear rate. The Couette flow of the semisolid material between two parallel plates is considered. The flow field is presented by momentum conservation equation. The non-Newtoniun behaviour of the semisolid material is expressed by the Herschel-Bulkley model. The agglomeration and de-agglomeration phenomena of the suspended particles in semisolid state under shear are represented introducing a time dependent structural parameter. The proposed model fitted well with existing work in a wide range of shear rates and could predict the flow and apparent viscosity of semisolid M2 steel. Finally, the work involves prediction of the flow field, rate of strain and apparent viscosity of the semisolid material under transient condition. It is observed that the time dependent viscosity is highly non-linear during step-change in shear rate. It is noticed that the structural parameter decreases as the shear rate is increased. Whereas, the apparent viscosity decreases with increasing shear rate but shows an undulation and after that gradually rises to a higher steady value as the plate velocity decreases suddenly.

Study on Thixotropic Property of A356 Alloy in Semi-Solid State

2012 ◽  
Vol 192-193 ◽  
pp. 335-340 ◽  
Author(s):  
Sudip Simlandi ◽  
Nilkanta Barman ◽  
Himadri Chattaopadhyay
Keyword(s):  
Shear Rate ◽  
Flow Field ◽  
Apparent Viscosity ◽  
Sudden Change ◽  
A356 Alloy ◽  
Momentum Conservation ◽  
Structural Parameter ◽  
Parallel Plates ◽  
Transient Nature ◽  
Semi Solid

In the present work, the thixotropic property of a semisolid aluminium alloy (A356) under deformation is investigated numerically where the Couette flow between two parallel plates is considered. The flow field is represented by momentum conservation equations where the non-Newtonian behavior of the semisolid material is represented by the Herschel-Bulkley model. The agglomeration and the de-agglomeration phenomena of the suspended particles under shear are represented using a time dependent structural parameter influenced by the rate of strain and shear stress. The simulation predicts the flow field, rate of strain and apparent viscosity of the semisolid materials under transient and steady state conditions. It is found that the apparent viscosity shows a transient nature during sudden change in the shear rate, and its value decreases with increasing shear rate and vice-versa. It is also found that the present prediction shows a good agreement with prior work.

Numerical Study of the Combined Free-Forced Convection and Mass Transfer Flow Past a Vertical Porous Plate in a Porous Medium with Heat Generation and Thermal Diffusion

2006 ◽  
Vol 11 (4) ◽  
pp. 331-343 ◽  
Author(s):  
M. S. Alam ◽  
M. M. Rahman ◽  
M. A. Samad
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Differential Equations ◽  
Forced Convection ◽  
Heat Generation ◽  
Numerical Study ◽  
Porous Plate ◽  
Integration Scheme ◽  
Suction Parameter ◽  
Transfer Flow

The problem of combined free-forced convection and mass transfer flow over a vertical porous flat plate, in presence of heat generation and thermaldiffusion, is studied numerically. The non-linear partial differential equations and their boundary conditions, describing the problem under consideration, are transformed into a system of ordinary differential equations by using usual similarity transformations. This system is solved numerically by applying Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. The effects of suction parameter, heat generation parameter and Soret number are examined on the flow field of a hydrogen-air mixture as a non-chemical reacting fluid pair. The analysis of the obtained results showed that the flow field is significantly influenced by these parameters.

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