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Measurements and a model for convective velocities in the turbulent boundary layer

Date

1973-10

Authors

Cliff, William C., author
Sandborn, Virgil A., author
National Aeronautics and Space Administration, publisher

Journal Title

Journal ISSN

Volume Title

Abstract

A physical model is presented which describes convective velocities within a flat plate turbulent boundary layer. A production zone concept similar to that which Kline has reported with his visualization techniques is used as a basis for the physical model. The production zone concept employs the idea that packets of turbulent fluid are generated near the viscous sublayer. These packets are found to be discernible from the mean motion and may move either outward from the production zone or inward depending on their circulation relative to the fluid surrounding the packet. The packets are predicted to travel with a convective velocity different from the local mean velocity throughout most of the boundary layer. The model also predicts that the convective velocities will be functions of wave number outside the production zone. The model predicts that the convective velocity profile approaches the mean velocity profile after a finite length or time period. After the finite length, the convective velocities are predicted to become independent of wave number. The model predicts that the asymptotic growth of the boundary layer will be a linear function of distance. Experimental results are presented which agree with the predictions of the model. Correlation concepts are used to measure the convective velocity. Convective velocity as a function of frequency indicates Taylor's hypothesis to be invalid for the turbulent boundary layer.

Description

CER73-74 WCC-VAS 61.
Includes bibliographical references.
Prepared for and sponsored by NASA - George C. Marshall Space Flight Center.
NASA technical note; D-7416.

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Subject

Turbulent boundary layer
Convection (Meteorology) -- Mathematical models

Citation

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