A comparison of properties of temporal and spatial temperature increments in a turbulent plane jet

The spatial longitudinal temperature correlation function obtained, on the center line of a turbulent plane jet in the self-preserving region of the flow, for separations extending up to about 13 Kolmogoroff microscales is in reasonable agreement with the temporal autocorrelation when Taylor’s hypothesis is used. The rms value of the spatial temperature derivative, inferred from the curvature at zero separation of the correlation, agrees well with the rms value of the time derivative. Other comparisons between temporal and spatial temperature increments include probability and spectral density functions. Reasonable agreement is found between fourth-order moments of these increments, but the magnitude of third-order moments is larger for spatial than temporal increments. Spectral density functions of spatial increments do not exhibit the periodicity in spectra of temporal increments.