Js. Kim et al., TECHNIQUE FOR THE EXPERIMENTAL ESTIMATION OF NONLINEAR ENERGY-TRANSFER IN FULLY-DEVELOPED TURBULENCE, Physics of plasmas, 3(11), 1996, pp. 3998-4009
A new procedure for calculating the nonlinear energy transfer and line
ar growth/damping rate of fully developed turbulence is derived. It av
oids the unphysically large damping rates typically obtained using the
predecessor method of Ritz [Ch. P. Ritz, E. J. Powers, and R. D. Beng
tson, Phys. Fluids B 1, 153 (1989)]. It enforces stationarity of the t
urbulence to reduce the effects of noise and fluctuations not describe
d by the basic governing equation, and includes the fourth-order momen
t to avoid the closure approximation. The new procedure has been imple
mented and tested on simulated, fully developed two-dimensional (2-D)
turbulence data from a 2-D trapped-particle fluid code, and has been s
hown to give excellent reconstructions of the input growth rate and no
nlinear coupling coefficients with good noise rejection. However, in t
he experimentally important case where only a one-dimensional (1-D) av
eraged representation of the underlying 2-D turbulence is available, t
his technique does not, in general, give acceptable results. A new 1-D
algorithm has thus been developed for analysis of 2-D measurements of
intrinsically 2-D turbulence. This new I-D algorithm includes the non
resonant wave numbers in calculating the bispectra, and generally give
s useful results when the width of the radial wave number spectrum is
comparable to or less than that of the poloidal spectrum. (C) 1996 Ame
rican Institute of Physics.