Near-Wall Strong Sweeps and High Kurtosis Levels
In direct numerical simulations of wall turbulence, i.e. channel, pipe and boundary layers, in general a very high near-wall value is found for the kurtosis of the wall-normal velocity fluctuations. For instance values up to ~25 have been reported, see e.g. (Kim et al., 1987). In contrast, the experimental data up to now have not confirmed such high kurtosis levels and give considerable lower values, say around ~5 (Durst et al., 1995). This has led to some controversy between numerical simulators and experimentalists to explain the background of this discrepancy. We aim to resolve this problem with help of data from a direct simulation together with experimental data.