APPROXIMATE LAMINAR SHEAR LAYER PROFILES FORMED BY COMBINATION OF UNIVERSAL FUNCTIONS.
CALIFORNIA UNIV BERKELEY COLL OF ENGINEERING
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An approximate relation existing between skin friction, displacement thickness and main-stream velocity-gradient parameters suggests that many low-speed laminar boundary layer profiles may be considered to comprise three universal functions in combustion. One of these functions resembles the law of the wake introduced by Coles into the analysis of turbulent flow. The distribution of skin friction along a solid wall with arbitrary mainstream velocity distribution can be calculated using the universal profiles in conjunction with the moment integral equation. As the resulting equation for skin friction must be integrated numerically, the paper includes a simple composite method in which the profile approximation is used to derive a two-parameter skin friction relation to complement the popular and reliable Thwaites momentum thickness formula. An attempt is made to determine limits on the utility of the profile representation. The criterion appears to be that a displacement thickness parameter must remain within a well-defined range. Procedures are given for cases outside this range.
- Fluid Mechanics