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Fluid flow across a cylinder at an angle

  1. Jul 28, 2015 #1
    Hello,

    I need some help with a problem in fluid mechanics. Consider a situation where a cylinder ( of a given radius and length) is kept at an angle theta to the vertical, and a fluid flows across this cylinder. I need to determine the forces and moments acting on this cylinder, for different values of the angle and the flow velocity. I wanted to know if any research has been done in this regard. I tried to find research papers, but couldn't find any paper that would help be get the values of the drag and lift forces as a function of the angle and the flow velocity. I'm not an expert at fluid mechanics, so I think I'm not searching at the right place or with the right keywords, and surely there must be some research done on this and subsequently papers which could give me the value of these forces. As of now, even if I don't get the moment values but only the variation of the drag and lift forces, even that will do.

    Would be really glad if someone could help. Thanks :)

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  3. Jul 28, 2015 #2

    SteamKing

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    Absolutely, research has been done on this question.

    In particular, current flow across submerged pipelines and cables comes to mind directly.

    I also recall that in the early days of flight, it was found that the wires which helped brace biplane wings together were found to create a relatively large amount of drag due to their circular cross section. Wires with more aerodynamic shape were developed which cut down on the amount of drag produced.

    This type of flow is also studied because the passage of fluid around the cylinder can also set up vibratory forces, which can cause fatigue in the material of the cylinder.
     
  4. Jul 28, 2015 #3

    SteamKing

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  5. Jul 28, 2015 #4

    boneh3ad

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    There has been a lot of research on this type of geometry. To find the forces, you will probably have to find someone who has done experiments on the geometry, as there won't be any good analytical way to determine that. There are a number of phenomena that will complicated finding such forces any way other than through experiments, including the effect of vortex shedding and the effect of boundary-layer transition on the surface.

    Interestingly enough, though, there exists a similarity solution for the boundary layer over this geometry. If you are at all interested in that, the relevant term to search would be "Falkner-Skan-Cooke boundary layer". That may be a little outside your scope here, though.

    You might try searching Google scholar for things such as "swept cylinder" or "yawed cylinder" with whatever other keywords you want (e.g. "drag on a swept cylinder"). Those are the most common terms you will find in the literature for this geometry. The problem is that you will need a subscription for most things that will pop up since most of it will be behind a pay wall.
     
  6. Jul 28, 2015 #5

    Baluncore

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    Being diagonal to the flow, the length of the cylinder will be effectively shortened.
    The section of the cylinder will appear to the fluid as an ellipse.
    google ' drag coefficient of ellipse '
     
  7. Jul 28, 2015 #6

    boneh3ad

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    That's not a good idea. Despite the fact that the cross section would be an ellipse, the flow over the swept cylinder would not be all that similar to an ellipse due to the fact that the pressure gradient creates a three-dimensional flow. It's pretty substantially different.
     
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