Calculating Film Thickness on Rotating Cylinders with Fluid Gap?

In summary, the conversation discusses a problem involving roll coating with two rotating cylinders of different speeds that do not touch but are close together. The question is whether it is possible to calculate the thickness of the film on each cylinder. The person who has been looking at the problem for a month believes it can be solved with the Navier-Stokes formulas, but they may be too difficult to calculate manually. The discussion also mentions the possibility of using numerical simulation software or experimental measurement to find a solution.
  • #1
Samy1977
4
0
I am trying to solve a problem concering roll coating. This is 2 rotating cylinders whith different speeds. The two cylinders are in the same horizontal plane. They don't touch each other, but are close together. On one cylinder there is a fluid. When the fluid goes through the gap, the point where the cylinders are closest to each other, both cylinders take some of the fluid. Is it possible to calculate how thick the film is on each cylinder??

I have looked a month at this problem now. I think it can be done with the Navier-Stokes formulas, but they could be too difficult to calculate manualy. I know it abolutely has something to do with the speed of the cylinders, and probably the gap between them.
 
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  • #2
Sorry but I cannot imagine your problem. Do you mind posting a picture of it?. It can be done in .bmp and clicking below in Manage Attachments. I don't know if the cylinders are concentric, parallel, and I don't understand what you mean with the closest point and "both cylinders take some of the fluid".
 
  • #3
stage.bmp]The problem[/URL]

At the top you see how the cylinders are located to each other. In the close up, the red is the fluid. One cylinder has all the fluid first, then it is divided between the two cylinders. I want to "know"/calculate the thickness one cylinder 1. Between the two blue arrows.
Hope it is clearer now. Sorry about the description, it is a bit difficult to describe.
 
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  • #4
Wow!

I'm sorry. To be honest, I think your problem is very difficult to be solved in a classical way. I will explain that:

Making your own numerical simulation with the N-S equations will be a serious challenge. It's a viscous free surface flow. The free surfaces flow are heavier to simulate, because you need a boundary condition between the fluid and the air.

My advice, if you want to listen it, is to use a commercial simulation software of Computational Fluid Dynamics. Surely Fluent 6.0 can solve your problem.

Your question is not trivial at all. :bugeye:

Another posibility would be to measure experimentally some fluid variables and to obtain the thickness by means of integral conservation laws.
 
  • #5
Thanks, that is what I thought. I had to verify.
 

Related to Calculating Film Thickness on Rotating Cylinders with Fluid Gap?

1. What is fluid flow through two cylinders?

Fluid flow through two cylinders refers to the movement of a fluid (such as water or gas) through two parallel cylinders. This flow can be either laminar (smooth and orderly) or turbulent (chaotic and irregular), and is dependent on factors such as the fluid's viscosity and the size and shape of the cylinders.

2. How does the flow rate of fluid through two cylinders affect the pressure?

The flow rate of fluid through two cylinders is directly related to the pressure. As the flow rate increases, the pressure decreases, and vice versa. This is known as Bernoulli's principle, which states that as the velocity of a fluid increases, the pressure decreases.

3. What factors can affect the flow of fluid through two cylinders?

Several factors can affect the flow of fluid through two cylinders, including the viscosity of the fluid, the diameter and length of the cylinders, and the pressure difference between the two ends of the cylinders. Other factors such as the surface roughness of the cylinders and the presence of obstacles can also impact the flow.

4. How can the flow of fluid through two cylinders be measured?

The flow of fluid through two cylinders can be measured using various methods, including flow meters, pressure gauges, and velocity probes. These instruments can provide information on the flow rate, pressure, and velocity of the fluid, allowing for accurate measurements of the flow.

5. What are some applications of studying fluid flow through two cylinders?

Studying fluid flow through two cylinders has various practical applications, such as in the design of pipes and channels for fluid transportation, the development of efficient turbines and engines, and the understanding of blood flow through arteries and veins. It is also essential in fields such as hydraulics, aerodynamics, and fluid mechanics.

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