Accession Number : AD0712375

Title :   DETECTION OF THE TURBULENT-NON-TURBULENT INTERFACE.

Descriptive Note : Interim technical rept. no. 1,

Corporate Author : JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICS

Personal Author(s) : Kibens,Valdis ; Kovasznay,Leslie S. G.

Report Date : JUN 1970

Pagination or Media Count : 66

Abstract : A new method was developed to form an intermittency function I(t) (ON for turbulent, OFF for non-turbulent flow) using an analog circuit. The detection process is based on a signal proportional to a spatial derivative of velocity; two adjustable detection parameters are used, namely, a threshold and a 'memory' or 'hold-time.' Methods are given for determining the optimum values of the detection parameters for a given flow using a two step procedure. First the detector cirucit performance is calibrated using a synthetic signal of known properties, and then measurements in the particular flow are related to the calibration tests to determine optimum settings. Detailed description is given of the detector circuit and of a circuit for generating a 'synthetic turbulence' signal. Methods of determining detection errors and difficulties met in using the detection method in particular flows are discussed. An analytic model of the detection process is presented. (Author)

Descriptors :   (*TURBULENCE, INTERFACES), DETECTION, FUNCTIONAL ANALYSIS, CIRCUITS, DETECTORS

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE