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The Boundary Layers in Fluids with Little FrictionThe vortices forming in flowing water behind solid bodies are not represented correctly by the solution of the potential theory nor by Helmholtz's jets. Potential theory is unable to satisfy the condition that the water adheres at the wetted bodies, and its solutions of the fundamental hydrodynamic equations are at variance with the observation that the flow separates from the body at a certain point and sends forth a highly turbulent boundary layer into the free flow. Helmholtz's theory attempts to imitate the latter effect in such a way that it joins two potential flows, jet and still water, nonanalytical along a stream curve. The admissibility of this method is based on the fact that, at zero pressure, which is to prevail at the cited stream curve, the connection of the fluid, and with it the effect of adjacent parts on each other, is canceled. In reality, however, the pressure at these boundaries is definitely not zero, but can even be varied arbitrarily. Besides, Helmholtz's theory with its potential flows does not satisfy the condition of adherence nor explain the origin of the vortices, for in all of these problems, the friction must be taken into account on principle, according to the vortex theorem.
Document ID
20050028493
Document Type
Other - NACA Technical Memorandum
Authors
Blasius, H.
Date Acquired
August 22, 2013
Publication Date
February 1, 1950
Publication Information
Publication: Zeitschrift fuer Mathematik und Physik
Volume: 56
Issue: 1
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
NACA-TM-1256
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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