Questions tagged [boundary-layer]

Use for boundary layer related topics, including laminar and turbulent flows

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Examples for the benefits and importance of having a Boundary Layer

I understand what a boundary layer is and how it is formed. Mostly these boundary layers are related to increasing skin friction drag of the body. Please could you give some examples that show the ...
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1answer
150 views

How can a small airflow that passes through a slots redirect all the outer flow?

If this is normal wing without slots behind wing will be huge wake; airflow will separate, which is very easy to predict. Why would the outer flow follow the wing's couture; how can a small airflow ...
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3answers
109 views

How does the turbulent boundary layer thickness affect separation?

I read that for a turbulent boundary layer, a thicker (turbulent) boundary layer separates earlier than a thinner (turbulent) boundary layer? Why is that? Or is it the other way around?
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2answers
140 views

Does flow separation starts earlier at higher airflow speeds?

For same AoA,will flow separation starts earlier (point of separation more upstream) at higher airflow speeds (=higher air inertia) compare to lower airflow speeds? High speed airflow has more air ...
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3answers
3k views

What is the difference between flow separation and turbulent flow?

For air flowing over a wing, both flow separation and turbulent flow involve disturbed flow next to the surface and smooth flow further away. At what point does one say "oh, this flow has changed ...
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1answer
5k views

What causes the adverse pressure gradient that leads to flow separation?

When reading about flow separation I generally see a diagram like this: imp source: Wikimedia commons This shows that the boundary layer slows as it passes over the wing, eventually creating an ...
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3answers
12k views

What is the effect of flow separation on lift, pressure distribution and drag?

Consider an airfoil (a wing) in an airflow. When angle of attack increases, at some point the flow start to separate from trailing edge. By increasing the angle of attack more, this separation area ...
8
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2answers
525 views

How much noise does flow separation cause?

I recently found the following image showing the different sources of noise in vehicles. I notice that Aerodynamics is actually quite a big part of vehicle noise, as shown below by the blue line: ...