THE MEASUREMENT OF TURBULENCE IN WATER 
by 
M. S. Macovsky 
INTRODUCTION 
The development of techniques for measuring the tur- 
bulence of fluid media has progressed more in the study of gaseous 
flow than of liquid flow. The David Taylor Modei Basin has re- 
cently undertaken the study of turbulence in water both for the 
purpose of advancing the basic understanding of the phenomenon in 
water, and for the purpose of applying any fruitful results to the 
analysis of model testing, and other hydrodynamic problems influ- 
enced by turbulence. This paper describes the techniques that 
have been applied to the study of turbulence in water, and the de- 
gree of progress and success of each. 
Although the practical importance of fully understanding 
the phenomenon of turbulence in water has been recognized, progress 
comparable to that made in air has not been accomplished. It has 
been only within recent years that the meaning of turbulence in 
model testing, for instance, has been appreciated. Producing the 
proper turbulent boundary layer in ship models is essential to 
accurate testing. Proper model testing is but one of the many 
reasons which have made the necessity of measuring turbulence in 
water essential to the Taylor Model Basin. 
A number of techniques for measuring turbulence in water 
have been suggested and a few of them have already been tried at 
TMB. Hot-wire methods similar to those used in wind tunnels, dye 
diffusion, and oil-drop injection techniques have been tried. Of 
these, the most promising is the hot wire. 
Bach of the techniques will be described, and the re= 
sults ilJustrated. First, however, the basic definitions of the 
turbulence parameters will be reviewed, 
MEANING OF TURBULENCE 
Turbulence, by definition, is a state of commotion and 
agitation, As applied to hydro- and aerodynamics, it is a state 
of fluid flow wherein random velocity fluctuations are superimposed 
upon the mean flow. To describe such motion, physicists resort 
to statistical methods, 
In its simplest form turbulence, such as might occur in 
an open channel behind uniform rectangular wire grids, may be 
isotropic. Only two parameters are required to describe the 
