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98.4F December 29, 2000 06:40

boundary layer thickness

When doing the boundary layer correction first the normal boundary layer thickness is calculated and from that the boundary layer displacement thickness is calculated. What's the difference between " normal boundary layer thickness" and "boundary layer displacement thickness " ? They sound similar to me.


Ghanshyam Singh December 29, 2000 08:23

Re: boundary layer thickness
#B.L. Thickness(delta) is the normal distance where velocity changes from zero to 0.99Uo.

#Displacement thickness(delta_star) is based on the mass flux balance and it can be defined as the distance by which the external streamlines are shifted because of the b.l. formation. It is equal to the distance (delta_star) such that deficit in discharge due to b.l. formation is equal to delta_star times the ambient velocity "Uo".


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