Talk:Skin friction drag: Difference between revisions
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I don't know exactly what this needs changing to to fix it, but the bottom section titled "drag" is a) apparently in ''pounds'' and b) Has Cf on both sides of the equation, leading to them cancelling and you being left with a load of variables multiplied together equaling one. I see these as problems with need fixing. |
I don't know exactly what this needs changing to to fix it, but the bottom section titled "drag" is a) apparently in ''pounds'' and b) Has Cf on both sides of the equation, leading to them cancelling and you being left with a load of variables multiplied together equaling one. I see these as problems with need fixing. |
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== Turbulent drag is not supposed to be less than laminar drag, with every other circumstances being the same == |
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Article says: |
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" |
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Turbulent flow suggests a faster rate of flow due to velocity increase and/or viscosity decrease relative to laminar flow. This results in a thinner boundary layer which, relative to laminar flow, depreciates the magnitude of friction force as the fluid flows over the object |
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" |
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A) That's clearly not the case since a thinner boundary layer would mean a greater tangential velocity gradient at the solid-fluid |
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boundary, thus, greater friction. |
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B) In addition to that, a turbulent boundary layer has a steeper tangential velocity profile just |
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because it's turbulent: the chaotic movement enhances the momentum diffusion. |
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C) Finally, the turbulent boundary layer is always thicker than a laminar boundary layer, et ceteris paribus. |
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This also increases the displacement thickness, and through it, the pressure drag. |
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Revision as of 21:02, 4 May 2016
I don't know exactly what this needs changing to to fix it, but the bottom section titled "drag" is a) apparently in pounds and b) Has Cf on both sides of the equation, leading to them cancelling and you being left with a load of variables multiplied together equaling one. I see these as problems with need fixing.
Turbulent drag is not supposed to be less than laminar drag, with every other circumstances being the same
Article says: " Turbulent flow suggests a faster rate of flow due to velocity increase and/or viscosity decrease relative to laminar flow. This results in a thinner boundary layer which, relative to laminar flow, depreciates the magnitude of friction force as the fluid flows over the object "
A) That's clearly not the case since a thinner boundary layer would mean a greater tangential velocity gradient at the solid-fluid boundary, thus, greater friction.
B) In addition to that, a turbulent boundary layer has a steeper tangential velocity profile just because it's turbulent: the chaotic movement enhances the momentum diffusion.
C) Finally, the turbulent boundary layer is always thicker than a laminar boundary layer, et ceteris paribus.
This also increases the displacement thickness, and through it, the pressure drag.