Similarity of intermittency characteristics of temperature and transverse velocity.
The intermittency characteristics of the longitudinal (u) and transverse (v) velocity and temperature (theta) at similar Taylor microscale Reynolds numbers have been compared in a turbulent round jet. We examine the scaling exponents zeta_{alpha}(n) ( alpha=u , v , and theta ) of structure functions (deltaalpha);{n} , the intermittency exponents micro_{alpha} based on individual and mixed sixth-order structure functions, the scaling exponents tau;{alpha}(n) of the locally averaged energy and temperature dissipation rates approximated by ( partial differentialalpha partial differentialx);{2} , the flatness factors of the derivatives partial differentialalpha partial differentialx , and the probability density functions (PDFs) of partial differentialalpha partial differentialx , the increment deltaalpha and ( partial differentialalpha partial differentialx);{2} . It is found that v and theta are similar in terms of their intermittency characteristics. They are more intermittent than u . The scaling exponent zeta_{v}(n) is marginally larger than zeta_{theta}(n) . The intermittency exponent micro_{theta} is smaller than micro_{v} based on the estimate of mixed sixth-order structure functions, while micro_{theta} is nearly equal to micro_{v} based on the estimate of individual sixth-order structure functions. The temperature dissipation rate is more intermittent than the turbulent energy dissipation rate, as indicated by tau;{alpha}(n) . The flatness factor of partial differentialtheta partial differentialx is marginally larger than that of partial differentialv partial differentialx . The PDFs of partial differentialtheta partial differentialx , deltatheta , and ( partial differentialtheta partial differentialx);{2} show the strongest departure from the Gaussian distribution.
Xu
G
G
School of Civil Engineering, University of Sydney, NSW 2006, Australia. ggxu@optusnet.com.au
Zhou
T
T
Rajagopalan
S
S