Longitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulence
Abstract
Streamwise evolution of longitudinal and transverse velocity structure functions in a decaying homogeneous and nearly isotropic turbulence is reported for Reynolds numbers Re_{λ} up to 720. First, two theoretical relations between longitudinal and transverse structure functions are examined in the light of recently derived relations and the results show that the loworder transverse structure functions can be well approximated by longitudinal ones within the subinertial range. Reconstruction of fourthorder transverse structure functions with a recently proposed relation by Grauer et al. is comparatively less valid than the relation already proposed by Antonia et al. Secondly, extended selfsimilarity methods are used to measure the scaling exponents up to order eight and the streamwise evolution of scaling exponents is explored. The scaling exponents of longitudinal structure functions are, at first location, close to Zybin's model, and at the fourth location, close to She—Leveque model. No obvious trend is found for the streamwise evolution of longitudinal scaling exponents, whereas, on the contrary, transverse scaling exponents become slightly smaller with the development of a steamwise direction. Finally, the stremwise variation of the orderdependent isotropy ratio indicates the turbulence at the last location is closer to isotropic than the other three locations.
 Publication:

Chinese Physics B
 Pub Date:
 January 2014
 DOI:
 10.1088/16741056/23/1/014701
 Bibcode:
 2014ChPhB..23a4701I