MEASUREMENT OF INTENSITY OF TURBULENCE 

 IN WATER BY DYE DIFFUSION 



by 



M„ So Macovsky, W. L. Stracke, and J. V. Wehausen 



ABSTRACT 



This report describes exploratory experiments which were 

 made to develop a means for measuring intensity of turbulence 

 in water by a method of dye diffusion analogous to the method 

 developed by Schubauer using heat diffusion in air. Although 

 the method was dropped before the experimental technique was 

 refined, the work completed indicates that the method can be 

 used under certain circumstances to give fairly reliable re- 

 sults. Some of the restrictions on the method, some necessary^ 

 improvements in the technique, and some methods of data correct 

 tion are discussed. * 



INTRODUCTION 



This report describes some exploratory experiments which 

 were made in order to develop a method for measuring turbulence 

 intensity in water by a method of dye diffusion analogous to 

 the heat diffusion method used by Schubauer (1)*. Although 

 the experiments were carried out somewhat crudely, they have 

 perhaps served their purpose in that they indicate that the 

 method can be used successfully and they point out the places 

 where greater care needs to be taken. The two values of in- 

 tensity obtained as a result of the experiments are in -fairly 

 good agreement with results obtained under the same circumstances 

 with a hot-wire velocity meter for water. The method was not 

 pursued further since a hot-wire velocity meter had been develop- 

 ed which was satisfactory for water and which was much more 

 versatile in use. 



It has been known for some time that the rate of diffusion 

 of a substance from a source in a turbulent stream can be used 

 to measure the intensity of the transverse component of the tur- 

 bulent fluctuations and also at least one of the several scales 

 of turbulence which may be defined. The theoretical justifica- 

 tions for the method was given by G. I. Taylor (2) (3) and the 

 method was used by Schubauer (1) to measure turbulence in a 

 wind tunnel from the measured temperature distribution behind 

 a heated wire. Diffusion methods have also been used in water 

 by Kalinske, Robertson, and Van Driest (4), (5), (6) in order to 

 determine the intensity of turbulence. In these experiments the 

 diffusing substance was small particles and their meanderings 



* Numbers in parentheses indicate references on page 13. 



