Yih-Ho Pao
Published: 1968
Total Pages: 10
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From the complete set of two-point covariance equations for the turbulent velocity and temperature fields, the spherically averaged spectra in stably stratified fluids are deduced for the entire locally homogeneous ranges of wave numbers, including buoyancy, inertial, and viscous subranges. The spectral equations are closed with a similarity hypothesis (Pao, 1965, 1968). The predicted spectral behavior in the buoyancy subrange can be summarized as follows: (1) the spectra in weakly stable fluids agree in general, although differ in detail, with those predicted by Bolgiano (1959), Monin (1962), Shur (1962), and Lumley (1964), that the velocity spectra are steeper than k to the -5/3 power and the temperature spectra are less steep than k to the -5/3 power; (2) in strongly stable fluids, both the velocity and the temperature spectra are wavy, which resemble certain spectral measurements in high altitude clear air turbulence (Reiter and Burns, 1966; Pinus, Shur and Vinnichenko, 1966; Crooks, Hoblit and Prophet, 1967). (Author).