In order to determine flow speed and direction, all possible cross-correlations are calculated at a distance of two fibers within three inner fiber rings. All correlations in the same direction are averaged, resulting in six correlation curves (30°, 90°, ..., 330°; by our definition, 0° means vertical flow direction). All six curves are fitted globally with the following model:
|
Parameter |
Description |
|---|---|
|
v |
The flow speed (fit parameter). |
|
ϕ |
The angle between the flow and the vector connecting the fibers in this group of cross-correlations (fit parameter). |
|
r0 |
The apparent distance between the fibers (calibration parameter). |
|
Gdiff(τ) |
The diffusion term (2D or 3D), see Fit Calculation. |
|
Other parameters are defined as for the fit calculations, see Fit Calculation. |
|