Twodimensional separating turbulent boundary layers
Abstract
It is shown that mean flow similarity based on a velocity scale related to the maximum shear stress (SchofieldPerry similarity) can accurately describe detached twodimensional turbulent boundary layers provided the origin of the similarity is relocated on the zero velocity streamline in the detached flow. In support of this, data from several different experiments are analyzed and presented. The failure of the standard logarithmic law to accurately describe flow close to the wall in a separating layer is discussed. It is argued that the failure of the logarithmic law is related to the nature of turbulent separation, which is not an event but a process in which the proportion of intermittent flow reversal near the wall gradually increases with distance downstream and therefore, the mean velocities measured within the detachment region contain a proportion of reversed flow which does not follow standard wall similarity. Experimental evidence supports another proposition that a twodimensional turbulent boundary layer detaches with a universal mean profile shape which is accurately described by SchofieldPerry similarity.
 Publication:

AIAA Journal
 Pub Date:
 October 1986
 DOI:
 10.2514/3.9491
 Bibcode:
 1986AIAAJ..24.1611S
 Keywords:

 Boundary Layer Separation;
 Computational Fluid Dynamics;
 Turbulent Boundary Layer;
 Two Dimensional Boundary Layer;
 Flow Velocity;
 Reattached Flow;
 Reversed Flow;
 Shear Stress;
 Similarity Theorem;
 Wall Flow;
 Fluid Mechanics and Heat Transfer