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No Slip Boundary conditions

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Old   May 27, 2008, 10:31
Default Hi People, I am trying to j
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Lawrence
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Hi People,

I am trying to justify my choice of no slip boundary conditions for a wall shear stress study:

(1) it simply means the fluid is not moving at the wall surface

(2) slip can be used if the shear components are specified, but will not be appropriate in this case since i am interested to find the wall shear stress

(3) the no slip boundary condition should account for highest wall shear stress compared to cases with slip, thus conservative results

Please correct me ( especially (3)) if i am wrong. any comments and helps will be very much appreciated.
cheers

Lawrence
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Old   May 27, 2008, 10:44
Default All 3 of your statements seem
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Edward Reed
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All 3 of your statements seem accurate to me.
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Old   May 27, 2008, 10:51
Default By turning on the no slip boun
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By turning on the no slip boundary condition you are essentially saying that the surface has roughness and so you will get a proper boundary layer profile. Without it, you won't get any surface shear stresses or any viscous drag.

(1) A boundary layer has zero velocity at the wall and tends to 0.99*Ufreestream at its edge. So, yes.

(2) I suppose you could, but why since it is a bit of a fudge? You need no-slip if you want to predict what these shear stresses are.

(3) Not sure what you mean here.

I find it strange you have to justify applying the no-slip condition, especially for a shear stress study. I thought it'd be more the case if it was the other way around.
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Old   May 27, 2008, 11:00
Default Hi Edward and Adriano, Than
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Lawrence
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Hi Edward and Adriano,

Thanks for your replies and help. Seems like no-slip Boundary condition is the right way to go for this case.

I am asking for help here because someone questioned my choice of such condition but now i will be much more confident when explaining the choice.

Cheers

Lawrence
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