Representation of Space-Time Velocity and Pressure Fluctuation Correlations by a Tentative Phenomenological Model

摘要

Some difficulties in synthesizing velocity perturbation fields from two-point space-time correlation measurements are discussed including the non-uniqueness of the representation and the effects of averaging. A phenomenological model of the fluctuating velocities based on damped travelling waves has been derived. This model is based on the physical mechanism of slow speed streak 'break-up', as taken from hydrogen bubble visualization data. The model compares quite well with the two-point space-time correlation of velocity perturbations. Furthermore, the form derived for the space-time velocity correlation function is exactly the same form as the best available empirical fit to the space-time wall pressure data. (Author)