Bin-centred difference scheme
From Atomix
For a bin-centred difference scheme:
- start at bin n = (nmax / 2) + 1
- start with <math>\delta</math> = 1
- if <math>\delta</math> is even compute the second order structure function D(n,<math>\delta</math>) as the segment mean of the square of the velocity difference between the bins separated by distance <math>\delta</math>r0 centered around bin n:
D(n, <math>\delta</math>) = <math>\langle</math> [v’(n+(<math>\delta</math>/2), t) - v’(n-(<math>\delta</math>/2), t)]2 <math>\rangle</math>
where the angled brackets indicate the mean across all t for the data segment yielding a velocity difference after the application of the Level 1 QC criteria - if <math>\delta</math> is odd compute the second order structure function D(n,<math>\delta</math>) as the segment mean of the mean of the square of the velocity difference between the bins separated by distance <math>\delta</math>r0 centered on the upper and lower extent of bin n:
dv'lo(n, <math>\delta</math>, t) = v’(n+floor(<math>\delta</math>/2), t) - v’(n-ceil(<math>\delta</math>/2), t)
dv'hi(n, <math>\delta</math>, t) = v’(n+ceil(<math>\delta</math>/2), t) - v’(n-floor(<math>\delta</math>/2), t)
where ceil and floor indicate the upper and lower integer value respectively, then
D(n, <math>\delta</math>) = <math>\langle</math> [dv'lo(n, <math>\delta</math>, t)2 + dv'hi(n, <math>\delta</math>, t)2] / 2 <math>\rangle</math>
the angled brackets again indicating the mean across all t in the data segment yielding a velocity difference after the application of the Level 1 QC criteria - increment <math>\delta</math> and repeat steps until <math>\delta</math> = nmax
- increment n and repeat steps until n + (nmax / 2) exceeds the bin number for which valid v’ are available
