AGE method simulations of a turbulent far‐wake compared to spectral DNS

Abstract

SUMMARYTurbulent ow simulation methods based on ÿnite di erences are attractive for their simplicity, exibility and e ciency, but not always for accuracy or stability. This paper demonstrates that a good compromise is possible with the advected grid explicit (AGE) method. Starting from the same initial ÿeld as a previous spectral DNS, AGE method simulations of a planar turbulent wake were carried out as DNS, and then at three levels of reduced resolution. The latter cases were in a sense largeeddy simulations (LES), although no speciÿc sub-grid-scale model was used. Results for the two DNS methods, including variances and power spectra, were very similar, but the AGE simulation required much less computational e ort. Small-scale information was lost in the reduced resolution runs, but large-scale mean and instantaneous properties were reproduced quite well, with further large reductions in computational e ort. Quality of results becomes more sensitive to the value chosen for one of the AGE method parameters as resolution is reduced, from which it is inferred that the numerical stability procedure controlled by the parameter is acting in part as a sub-grid-scale model.