Modeling of Spatial Resolution Effects Using Dns of Turbulent Channel Flow

In this study, the effect of limited spatial resolution of hot wire anemometry (HWA) is investigated through analysis of the two dimensional energy spectra from direct numerical simulation (DNS) of turbulent channel flow at Reτ ≈ 934. Various spanwise filter lengths are applied to the streamwise velocity component in order to mimic the spatial resolution of the HWA experiments. The overall effect of insufficient spatial resolution causes attenuation of the smallscale energy levels in experimental data. The attenuated energy clearly increases as the wire-length is increased and the filtered DNS results show good agreement. It is shown that small-scale energy levels are highly attenuated in the near-wall region. We introduce an empirical expression to estimate the amount of the missing energy as a function of wire length and wall-normal distance. This expression can be used to correct experimental data for the effects of attenuation due to spatial resolution to obtain a more accurate energy spectra and turbulence intensity.