Inlet perturbation

Linfeng

Hi,

I am wondering how to generate inlet perturbations that satisfy a given energy spectrum, since, as you know, in LES of spatially developing flows such as mixing layers and jets, the random perturbation at the inlet section is crucial for the development of coherent structures.

It is easy to generate initial conditions for temporally growing flows. But for spatially growing ones, it seems impractical to firstly generate a perturbation field and then use the Taylor's frozen-turbulence hypothesis. So what are the tricks here?

thanks in advance