Lj. Peltier et Jc. Wyngaard, STRUCTURE-FUNCTION PARAMETERS IN THE CONVECTIVE BOUNDARY-LAYER FROM LARGE-EDDY SIMULATION, Journal of the atmospheric sciences, 52(21), 1995, pp. 3641-3660
The conventional theory of the scattering of transmitted acoustic, mic
rowave, and optical radiation by turbulence uses the refractive index
structure-function parameter C(N)2. The authors calculate the vertical
profiles of the structure-function parameters on which C(N)2 depends,
those for temperature and humidity, C(T)2 and C(Q)2, and their joint
structure-function parameter, C-TQ, from large-eddy simulation (LES) d
ata for convective boundary layers. The results agree well with experi
mental measurements. Modern views of wave propagation through turbulen
ce with substantial intermittency, such as that found in the high Reyn
olds number flows in geophysics, suggest that the structure-function p
arameter be interpreted as a local flow variable rather than the tradi
tional ensemble average. Through the refined Kolmogorov-Obukhov simila
rity hypotheses, a set of local structure-function parameters is defin
ed that depends on locally averaged values of the molecular destructio
n rates of velocity and scalar variances. Through analysis of the loca
lly averaged variance budgets, the coupling between the resolvable-sca
le fields in LES and these local destruction rates are outlined, with
the focus on scalars. Using data from direct numerical simulation, we
test two models of the locally averaged destruction rate of scalar var
iance. Each emulates its approximately lognormal statistics and can be
used with LES codes, enabling predictions of local structure-function
parameter fields.