Nearly every discussion in the literature
of turbulence and its associated energy cascade seems to bring
up the following verse:
"Big whirls have little whirls that feed on their
velocity;
And little whirls have lesser whirls, and so on to viscosity
- in the molecular sense"
quoting eminent polymath Lewis Frye Richardson in his
1922 text "
Weather Prediction by Numerical Processes." That this quotation makes its
appearance so ubiquitously gives credence to its importance.
The aim of the following web pages is to elucidate some of the
basic physical concepts (namely, the turbulent energy cascade)
described by Richardson's 90+ year-old jingle from a more
physical perspective, and also to present a technique called
large-eddy simulation (LES) which hopes to model them.