integralScale: Integral length scale calculation of turbulent flows.

In tunelipt/wutils: Useful functions for data processing in a wind tunnel

Description

Calculates the integral length scale.

Usage

integralScale(u, spans = NULL, nn = NULL, degree = 4, plt = FALSE,
  verbose = TRUE)

Arguments

u	Time series containing velocity.
spans	Filtering parameters to be passed to spec.pgram.
nn	Number of times of the peak frequency to use to clip the spectrum.
degree	Degree of polynomial that will be fitted to the spectrum.
plt	Whether the spectrum should be plot.
verbose	Print calculation info?

Details

Uses equation XYZ from Semiu and Scanlan book to compute the integral length scale:

L = 1/(2.pi) Um / f_peak

The spectrum is computed using spec.pgram and parameter spans is passed to this function to smooth the spectrum. If parameter nn is NULL, all points of the spectrum is fitted. If it is an integer, the point os maximum spectral density is found (f_peak) and the spectrum is fitted using only points whose frequency is smaller than nn.f_peak. The log of spectral density and log of frequency are than fitted to a degree degrees polynomial and the peak frequency is calculated and used to calculate the integral length scale.

Value

Integral length scale.

Author(s)

Paulo José Saiz Jabardo

See Also

spec.pgram lm

tunelipt/wutils documentation built on Nov. 5, 2019, 11:01 a.m.