What is Couette viscometer?
What is Couette viscometer?
The Couette viscometer is a well-known apparatus designed to measure the viscosity of a fluid that consists of two coaxial rotating cylinders whose relative motion leads to shear the fluid enclosed between both cylinders.
How does a Couette viscometer work?
A viscometer in which the liquid whose viscosity is to be measured fills the space between two vertical coaxial cylinders, the inner one suspended by a torsion wire; the outer cylinder is rotated at a constant rate, and the resulting torque on the inner cylinder is measured by the twist of the wire.
Is Couette flow rotational?
Taylor–Couette flow is a flow between two rotating, infinitely long, coaxial cylinders.
Why is there no pressure gradient in Couette flow?
Recall that this result is obtained based on the assumption that the flow is steady, incompressible and laminar. For simple shear flow, there is no pressure gradient in the direction of the flow. The fluid motion is simply created by the moving top plate, and the velocity profile is linear (u = Uy/h).
What is a stormer viscometer?
The stormer viscometer measures the viscosity of a fluid by measuring the time taken for an inner cylinder in the mechanism to perform a fixed number of revolutions in response to an actuating weight.
What is cone and plate viscometer?
Cone and plate viscometers or viscosimeters are rotational viscometers that use a narrow-angled cone placed on a horizontal flat plate. The generator of the cone makes a very small angle, one to two degrees to the plate. The wedge-like space between the cone and the plate is filled with liquid to be investigated.
What does rheology describe?
Rheology is the science of measurement of deformation. Virtually all materials deform in response to an imposed stress (‘everything breaks if you hit it hard enough’) and the materials present in the eye range from liquid-like to soft-solid behaviour.
What is planar Couette flow?
Couette and planar Poiseuille flow are both steady flows between two infinitely long, parallel plates a fixed. distance, h, apart as sketched in Figures 1 and 2.
What is Couette flow and Poiseuille flow?
Combined Couette / Poiseuille flow is the steady flow between two flat plates, a fixed distance apart, in which the plates move relative to each other and there is a pressure gradient parallel to the plates. It is useful to bear this flow in mind when considering boundary layers next.
Is Couette flow incompressible?
IT is well known that mi exact solution of the Navier-Stokes equations exists for a viscous incompressible fluid in the case of plane Couette flow.
How does a stormer rotating cylinder viscometer work?
One type of rotating cylinder viscometer, called a Stormer viscometer, uses a falling weight, to cause the cylinder to rotate with an angular velocity.
What kind of viscometer is used for Couette flow?
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.
How are viscosities measured in a rotating viscometer?
Among the different possible ways to measure viscosities in rotating viscometers, the coaxial cylinder apparatus is the most commonly used in practice. The measured liquid intersperses the annular gap between the stationary inner cylinder (bob) and the rotating outer cylinder (cup).
What is the shear rate of a Couette flow?
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.
What is the effect of serum in a viscometer?
Serum is a good but undefined shear protectant. It promotes better cell growth in agitated and/or aerated cultures in a dose-dependent fashion up to 10% (v/v) (Papoutsakis, 1991b). Several studies employing bioreactors and well-defined Couette flows in a viscometer have shown that the protective effect of serum is…
