C. Jin, I. Potts, D. C. Swailes, M. W. Reeks 38 0.0 0.5 1.0 1.5 2.0 z/D 0.2 0.0 0.2 0.4 0.6 0.8 R ( a ) u ′ v ′ 0.0 0.5 1.0 1.5 2.0 z/D 0.2 0.0 0.2 0.4 0.6 0.8 R ( b ) u ′ v ′ 0.0 0.5 1.0 1.5 2.0 z/D 0.2 0.0 0.2 0.4 0.6 0.8 R ( c ) u ′ v ′ 0.0 0.5 1.0 1.5 2.0 z/D 0.2 0.0 0.2 0.4 0.6 0.8 R ( d ) u ′ v ′ Fig. 15: Auto-correlation of streamwise and crosswise velocity fluctutations as a function of spanwise length (a) C1 , (b) C2 , (c) C3 , (c) C4 ,