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The fluctuation of total injected power in turbulent flow have been studied in two experimental devices : the Rayleigh--Benard convection and the Von K' arm' an swirling flow between two
 

Summary: abstract
The fluctuation of total injected power in turbulent flow have been studied in two experimental
devices : the Rayleigh--Benard convection and the Von K' arm' an swirling flow between two
counter--rotating disk [1]. Original measurments of drag on a moving blade in a Von K' arm' an
flow, of thermal flux , temperature and its gradient integrated on a line in convection, show large
scale spatial correlations in energy injection mechanisms.
Those correlations are inconsistent with some assumption usually made to predict the general
behaviour of the relative fluctuations of global variables when turbulence grow [2]. With three
different convective cells and various fluids, we have measure a power laws for relative fluctuations
of some global variables on a large Rayliegh number range. For instance, we exhibit a striking
linear relation between the standart deviation of thermal flux and the temperature difference at
the boundaries.
In the last part, we try to test the prediction of the Evans, Cohen, Morriss's law about power
injected in non--equilibrium dissipative systems [3, 4]. To wit, we have studied : the Burridge--
Knopoff model of a chain of blocks pulled on a rough surface with a non linear friction force [5],
the simulation of 2D vibrated granular media [6], the GOY shell model [7] and our experimental
data of power injected in turbulent flows.
R'ef'erences
[1] R. Labb'e, J.­F. Pinton, S. Fauve 1996, Journal de Physique II, vol 35
[2] U. Frisch 1995, 'Turbulence', Cambridge University press.

  

Source: Aumaître, Sébastien - Laboratoire de Physique Statistique, Département de Physique, École Normale Supérieure

 

Collections: Physics