Fluids Viscosity: Calculating with a Flat Plate Viscometer

In summary, the conversation discusses the use of a flat plate viscometer to determine the viscosity of a liquid between two plates. The torque required to drive the rotating disc is given, and the member presents their attempt at a solution which involves finding the angular velocity and using an equation to calculate viscosity. However, the post is from 2007 and the member has not returned to the forum, so the thread is being closed.
  • #1
suspenc3
402
0

Homework Statement



A flat plate viscometer consists of a disc of diameter 50mm rotating at 300rpm in close proximity to a fixed horizontal plate. When the gap between the plates is 0.1mm, it is found that the torque required to drive the disc is 0.2Nm. What is the viscosity of the liquid between the plates?


The Attempt at a Solution



First I found the angular velocity to be 31.41 rad/sec, and then used U=rw to find the constant velocity (r=radius, w=angular velocity)

Next i used [tex]\tau = \mu(U/t)[/tex], knowing the torque, velocity and gap thickness to give me the viscosity [tex]\mu[/tex]

Does this look somewhat right?
 
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  • #2
Can we try F= μ (dv/dx) a, where a - area , μ - viscosity...
converting 31.41 rad/s (given) into liner velocity
Just high level thought... Not sure i am not correct path...
 
  • #3
suspenc3 said:

Homework Statement



A flat plate viscometer consists of a disc of diameter 50mm rotating at 300rpm in close proximity to a fixed horizontal plate. When the gap between the plates is 0.1mm, it is found that the torque required to drive the disc is 0.2Nm. What is the viscosity of the liquid between the plates?

The Attempt at a Solution



First I found the angular velocity to be 31.41 rad/sec, and then used U=rw to find the constant velocity (r=radius, w=angular velocity)

Next i used [tex]\tau = \mu(U/t)[/tex], knowing the torque, velocity and gap thickness to give me the viscosity [tex]\mu[/tex]

Does this look somewhat right?
Show more of the details. I can't tell you whether you did it right until I see your derivation of the algebraic equation for the torque.

Chet
 
  • #4
Saurav.1905 said:
Can we try F= μ (dv/dx) a, where a - area , μ - viscosity...
converting 31.41 rad/s (given) into liner velocity
Just high level thought... Not sure i am not correct path...
This was a post from 2007, and the member who originally posted this had not been back since. I think 8 years is enough. I'm closing this thread.

Chet
 

Related to Fluids Viscosity: Calculating with a Flat Plate Viscometer

What is a flat plate viscometer and how does it work?

A flat plate viscometer is a device used to measure the viscosity of fluids. It consists of a flat plate with a small gap between the plate and a stationary plate. The fluid is placed in the gap and a force is applied to the top plate. The resulting movement of the top plate is used to calculate the viscosity of the fluid.

What is viscosity and why is it important to measure?

Viscosity is a measure of a fluid's resistance to flow. It is important to measure because it affects the performance and behavior of fluids in various applications such as lubrication, mixing, and pumping. It is also a key property in understanding the flow of fluids in pipes and channels.

How is viscosity calculated using a flat plate viscometer?

The viscosity is calculated using the equation: Viscosity = (Force * Gap * Plate Length) / (Plate Velocity * Plate Width). The force, gap, plate length, and plate width are known values, while the plate velocity is measured using the device. By plugging in these values, the viscosity can be calculated.

What factors can affect the accuracy of viscosity measurements using a flat plate viscometer?

Factors that can affect the accuracy of viscosity measurements include temperature, pressure, and the type of fluid being measured. The device should be calibrated for the specific fluid being tested and the measurements should be taken at a consistent temperature and pressure to ensure accuracy.

What are some common applications of flat plate viscometers?

Flat plate viscometers are commonly used in industries such as oil and gas, chemical, and food processing to measure the viscosity of various fluids. They are also used in research and development to study the properties of new fluids and to optimize their performance in different applications.

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