A NOVEL METHOD FOR DIAGNOSING THE GROWTH OF SUBRESOLUTION-SCALE PERTURBATIONS

We have demonstrated a technique for diagnosing the growth of subresol ution-scale perturbations by the appearance of longer-wavelength, coup led modes once the growth has proceeded into the nonlinear regime. Com parison of the growth rate of this larger scale feature with numerical simulations can then be used to infer the growth rates of the initial perturbations. This experiment was conceived as an analog of large-sc ale computer simulations where the large eddy approximation is applied . There a subgrid-scale model is used to represent the effects of smal l scales on large-scale motion, which is directly numerically simulate d. (C) 1997 American Institute of Physics.