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Couette

If a fluid is placed between two concentric cylinders, and the inner cylinder rotated, a complex fluid dynamical motion known as Taylor-Couette flow is established. Mass transport is then by exchange between eddy vortices which can, under some conditions, be imagmed as a substantially enlranced diflfiisivity (typically with effective diflfiision coefficients several orders of magnitude above molecular difhision coefficients) that can be altered by varying the rotation rate, and with all species having the same diffusivity. Studies of the BZ and CIMA/CDIMA systems in such a Couette reactor [45] have revealed bifiircation tlirough a complex sequence of front patterns, see figure A3.14.16. [Pg.1112]

Figure A3.14.16. Spatiotemporal complexity in a Couette reactor space-time plots showing the variation of... Figure A3.14.16. Spatiotemporal complexity in a Couette reactor space-time plots showing the variation of...
Evans D J 1983 Computer experiment for nonlinear thermodynamics of Couette flow J. Chem. Phys. 78 3297-302... [Pg.2283]

Simulation of the Couette flow of silicon rubber - generalized Newtonian model... [Pg.151]

Figure 5.10 (a,b) Comparison of the simulated die swell in a Couette flow for the power-... [Pg.155]

Rotating cone viscometers are among the most commonly used rheometry devices. These instruments essentially consist of a steel cone which rotates in a chamber filled with the fluid generating a Couette flow regime. Based on the same fundamental concept various types of single and double cone devices are developed. The schematic diagram of a double cone viscometer is shown in... [Pg.160]

In the Couette flow inside a cone-and-plate viscometer the circumferential velocity at any given radial position is approximately a linear function of the vertical coordinate. Therefore the shear rate corresponding to this component is almost constant. The heat generation term in Equation (5.25) is hence nearly constant. Furthermore, in uniform Couette regime the convection term is also zero and all of the heat transfer is due to conduction. For very large conductivity coefficients the heat conduction will be very fast and the temperature profile will... [Pg.163]

Cottrell equation Cottrell unit Couchman equation Couette flow Couette viscometers Cough drops Coughlozenges... [Pg.256]

In packed beds of particles possessing small pores, dilute aqueous solutions of hydroly2ed polyacrylamide will sometimes exhibit dilatant behavior iastead of the usual shear thinning behavior seen ia simple shear or Couette flow. In elongational flow, such as flow through porous sandstone, flow resistance can iacrease with flow rate due to iacreases ia elongational viscosity and normal stress differences. The iacrease ia normal stress differences with shear rate is typical of isotropic polymer solutions. Normal stress differences of anisotropic polymers, such as xanthan ia water, are shear rate iadependent (25,26). [Pg.140]

Fig. 15. Flow pattern in rotating Couette flow where and Q2 represent the outer and inner rotational speeds. Fig. 15. Flow pattern in rotating Couette flow where and Q2 represent the outer and inner rotational speeds.
The study of flow and elasticity dates to antiquity. Practical rheology existed for centuries before Hooke and Newton proposed the basic laws of elastic response and simple viscous flow, respectively, in the seventeenth century. Further advances in understanding came in the mid-nineteenth century with models for viscous flow in round tubes. The introduction of the first practical rotational viscometer by Couette in 1890 (1,2) was another milestone. [Pg.166]

The RMS-800 provides steady-shear rotational rates from 10 to 100 rad/s and oscillatory frequencies from 10 to 100 rad/s. An autotension device compensates for expansion or contraction. With the standard 25- and 50-mm parallel plates, the viscosity range is 50-10 mPa-s, and the shear modulus range is 8 x 10 to 10 N/m. These ranges can be expanded with nonstandard plates, cones, and a Couette system. The temperature range is 20-350°C (-150 0 optional). [Pg.202]

For extremely narrow openings (cracks) with deep flow paths (such as mortar joints and tight-fitting components) the flow is laminar and the flow rate, Q (mVs), can be described by the Couette flow equation - ... [Pg.581]

Under steady-state conditions, as in the Couette flow, the strain rate is constant over the reaction volume for a long period of time (several hours) and the system of Eq. (87) could be solved exactly with the matrix technique developed by Basedow et al. [153], Transient elongational flow, on the other hand, has two distinctive features, i.e. a short residence time (a few ps) and a non-uniform flow field, which must be incorporated into the kinetics equations. In transient elongational flow, each rate constant is a strongfunction of the strain-rate which varies with time in the Lagrangian frame moving with the center of mass of the macromolecule the local value of the strain rate for each spatial coordinate must be known before Eq. (87) can be solved. [Pg.140]

This velocity profile is commonly called drag flow. It is used to model the flow of lubricant between sliding metal surfaces or the flow of polymer in extruders. A pressure-driven flow—typically in the opposite direction—is sometimes superimposed on the drag flow, but we will avoid this complication. Equation (8.51) also represents a limiting case of Couette flow (which is flow between coaxial cylinders, one of which is rotating) when the gap width is small. Equation (8.38) continues to govern convective diffusion in the flat-plate geometry, but the boundary conditions are different. The zero-flux condition applies at both walls, but there is no line of symmetry. Calculations must be made over the entire channel width and not just the half-width. [Pg.290]

Velocity profiles of Plane Couette flow — Continuum - - - First-otder slip Boltzmann Eq... [Pg.100]

Fig. 4—Comparison of velocity profiles of plane Couette flow between different models. Fig. 4—Comparison of velocity profiles of plane Couette flow between different models.
It should be pointed out that the flow rate in the case of the Couette flow is independent of the inverse Knudsen number, and is the same as the prediction of the continuum model, although the velocity profiles predicted by the different flow models are different as shown in Fig. 4. The flow velocity in the case of the plane Couette flow is given as follows (i) Continuum model ... [Pg.100]

Figure 3 illustrates some additional capability of the flow code. Here no pressure gradient is Imposed (this is then drag or "Couette flow only), but we also compute the temperatures resulting from Internal viscous dissipation. The shear rate in this case is just 7 — 3u/3y — U/H. The associated stress is.r — 177 = i/CU/H), and the thermal dissipation is then Q - r7 - i/CU/H). Figure 3 also shows the temperature profile which is obtained if the upper boundary exhibits a convective rather than fixed condition. The convective heat transfer coefficient h was set to unity this corresponds to a "Nusselt Number" Nu - (hH/k) - 1. [Pg.274]

Figure 3. Finite element simulation of plane Couette flow with thermal dissipation and conductive heat transfer. (f) — fixed temperature condition (c) — convective boundary condition. Figure 3. Finite element simulation of plane Couette flow with thermal dissipation and conductive heat transfer. (f) — fixed temperature condition (c) — convective boundary condition.
At the 24th Combushon Symposium, Shy et al. [26] introduced an experimental aqueous autocatalytic reaction system to simulate the premixed turbulent combustion in a well-known Taylor-Couette (TC) flow field. By electrochemically inifiafing fhis reachon system, the... [Pg.116]

The attractive feature of LADM Is that once the fluid structure Is known (e.g., by solution of the YBG equations given In the previous section or by a computer simulation) then theoretical or empirical formulas for the transport coefficients of homogeneous fluids can be used to predict flow and transport In Inhomogeneous fluid. For diffusion and Couette flow In planar pores LADM turns out to be a surprisingly good approximation, as will be shown In a later section. [Pg.262]

For the steady, planar Couette flow to be examined In a later section, the momentum balance equation yields... [Pg.265]

Couette Flow Simulation. MD typically simulate systems at thermodynamic equilibrium. For the simulation of systems undergoing flow various methods of nonequilibrium MD have been developed (Ifl iZ.). In all of these methods the viscosity Is calculated directly from the constitutive equation. [Pg.267]

The nonequilibrium MD method we employed ( ) is the reservoir method (iff.) which simulates plane Couette flow. The effective viscosity Is calculated from the constitutive relation... [Pg.267]

We simulated two systems (1) bulk fiuld (no wall potential) at equilibrium and undergoing Couette fiow, and (2) fiuld confined between planar micropore walls at equilibrium and undergoing Couette fiow. [Pg.268]

The shear stress Is uniform throughout the main liquid slab for Couette flow ( ). Therefore, two Independent methods for the calculation of the shear stress are available It can be calculated either from the y component of the force exerted by the particles of the liquid slab upon each reservoir or from the volume average of the shear stress developed Inside the liquid slab from the Irving-Kirkwood formula (JA). For reasons explained In Reference (5) the simpler version of this formula can be used In both our systems although this version does not apply In general to structured systems. The Irvlng-Klrkwood expression for the xy component of the stress tensor used In our simulation Is... [Pg.269]

Flow systems. In this subsection we present the results of our Couette flow simulations. Most of these results were first presented In Reference ( ). [Pg.275]


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Bob (Couette) Viscometer

Circular Couette Flow - A One-Dimensional Analog to Unidirectional Flows

Circular Couette flow

Coaxial Cylinder Couette Flow

Couette Shear Flow between Coaxial Cylinders

Couette and Poiseuille Flow

Couette apparatus

Couette birefringence

Couette cell

Couette cylinder geometry

Couette device

Couette flow

Couette flow Taylor number

Couette flow analysis

Couette flow anisotropic fluid

Couette flow apparatus

Couette flow apparent viscosity

Couette flow approximation

Couette flow birefringence

Couette flow equation

Couette flow instability

Couette flow nematic liquid crystal

Couette flow numerical solution

Couette flow reactor

Couette flow simulations

Couette flow technique

Couette flow viscometer

Couette flow, noise

Couette geometry

Couette granulator

Couette instability

Couette method

Couette mixer

Couette reactor

Couette rotating-cylinder viscometer

Couette shear field

Couette shear rate

Couette streaming

Couette striation thickness

Couette symmetry

Couette system

Couette test system

Couette type flow

Couette viscometer

Couette viscosimeter

Couette, Maurice Frederic Alfred

Couette-Taylor flow reactors

Couette-Taylor reactor

Couette-Taylor vortex

Couette-Taylor vortex flow reactor

Couette-Taylor vortex flow reactor continuous

Couette-shear flow

Couette-type device

Couette-type viscometers

Double Couette

Hagenbach-Couette correction

Importance of Angular-Momentum Conservation Couette Flow

Normal Stresses in Couette Flow

Planar Couette flow

Planar Couette geometry

Plane Couette flow

Plane-parallel Couette flow

Predicting the Striation Thickness in a Couette Flow System - Shear Thinning Model

Quantitative Visualization of Taylor-Couette-Poiseuille Flows with MRI

Reactors Couette flow reactor

Rheometer Couette

Rotational Couette flow

Shear Heating in Couette Flow

Stability Couette flow,

Stability Taylor-Couette instability

Taylor-Couette apparatus

Taylor-Couette flow

Taylor-Couette flow field

Taylor-Couette flow instability

Taylor-Couette geometry

Taylor-Couette vortex flow

Taylor-Couette-Poiseuille Flow

Taylor—Couette instability,

The Couette Viscometer

The Couette or Concentric Cylinder

Thermomechanical coupling in a Couette flow between parallel plates

Thermomechanical coupling in a circular Couette flow

Velocity profiles, couette flow

Velocity profiles, couette flow simulations

Viscosity determination from Couette

Viscosity, couette flow simulations

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