Fig 9.
pdfs of the scalar (a) and velocity (c) derivatives measured along their respective mean gradients. The pdfs are not symmetrical: asymmetry is observed at the third moment for the scalar (b), and at the fifth moment for the velocity (d). The anisotropy appears to be independent of Reynolds number (17, 21). In a and b, x ≡ ∂θ/∂y/〈(∂θ/∂y)2〉1/2, and in c and d, z ≡ ∂u/∂y/〈(∂u/∂y)2〉1/2. [a and b, Reproduced with permission from ref. 17 (Copyright 1994, American Institute of Physics).] [c and d, Reproduced with permission from ref. 21 (Copyright 2000, American Institute of Physics).]