#
On the RNG Theory of Turbulence

S. H. Lam
##
Abstract

The Yakhot and Orszag RNG theory of turbulence has generated
a number of scaling law constants in reasonable quantitative agreement
with experiments. The theory itself is highly mathematical, and its assumptions
and approximations are not easily appreciated, particularly since several
rather unconventional artifices are employed. The present paper reviews
the RNG theory and recasts it in more conventional terms using a distinctly
different viewpoint. A new formulation based on an alternative interpretation
of the origin of the random force is presented, showing that the artificially
introduced e in the original theory is an adjustable parameter, thus offering
a plausible explanation for the remarkable record of quantitative success
of the so-called e-expansion procedure.

published in *Physics of Fluids* A **4**, pp.1007-1017, May,
1992.
See Ye Zhou's "**Classical closure and Lam's interpretation of epsilon-renormalization
group theory**," *Physical Review E*, Volume **51**, Number 4,
April, 1995.

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