The Influence of Rainflow Filtering on the Distributions of Characteristic
Centre for Mathematical Sciences
Lund Institute of Technology,
Calculation of the exact distributions for characteristic wave parameters
by means of the regression-approximation method requires as input a spectral
density. The high-frequency cut-off in the spectrum plays an important role
for such computations. We use the rainflow filter as an alternative to the
band-pass filters traditionally used. The rainflow filter is a non-linear
filter which can be used to eliminate small-amplitude oscillations in a signal.
For a spectrum of JONSWAP type, the joint distribution of crest height and
crest period is calculated, and the filtering approaches are compared. The
rainflow filter yields results which are closer to the distributions obtained
from a spectrum with high-frequency content.
wavelength, wave period, rainflow cycle, filtering, spectrum