Statistical analysis result
When statistically analyzing displacement vectors in the “Evaluation” window the result cab be exported in a data file for making plots with the Tecplot software. When processing vectors resulting from LID PIV images, the Tecplot data file consists of two zones for the image coordinate and the physical coordinate, respectively. Additional two zones are used for uncertainty data, when processing a group of vector maps. Following are variable definitions of the rest columns:
x - Position of interrogation point in x-direction;
y - Position of interrogation point in y-direction;
Valid(%) - Percentage of the valid vector numbers at the interrogation point;
U - Mean displacement/velocity component in x-direction;
V - Mean displacement/velocity component in y-direction;
W - Mean displacement/velocity component in z-direction;
uu - Mean square fluctuations of U (normal Reynolds stress in x-direction);
vv - Mean square fluctuations of V (normal Reynolds stress in y-direction);
ww - Mean square fluctuations of W (normal Reynolds stress in z-direction);
uv - Mean product of U and V fluctuations (shear Reynolds stress in xy-plane);
uw - Mean product of U and W fluctuations (shear Reynolds stress in xz-plane);
vw - Mean product of V and W fluctuations (shear Reynolds stress in yz-plane);
The extension name of the data file is “.dat”. Following is an example of the data file for statistical analysis results.
TITLE="Statistical analysis of PIV data "
VARIABLES="x" "y" "Valid(%)" "U" "V" "W" "uu" "vv" "ww" "uv" "uw" "vw"
ZONE T="Image coordinate (pixel)" I=63 J=63 F=POINT
16 1008 40.00 2.9636 -2.9553 2.9345 1.382262e-003 2.728637e-003 5.712545e-003 1.262497e-004 2.568925e-003 -1.200566e-004
32 1008 60.00 2.9705 -2.9579 2.9510 1.049616e-003 2.808606e-003 4.542829e-003 6.131524e-005 1.996988e-003 -2.935055e-004
48 1008 60.00 2.9895 -2.9600 2.9873 1.000038e-004 2.537971e-003 4.052141e-004 1.446324e-004 1.382427e-004 2.405033e-005
. . .
ZONE T="Physical coordinate (mm, m/s, m^2/s^2)" I=63 J=63 F=POINT
1.562500e+000 9.843750e+001 4.000000e+001 1.447056e+002 -1.443020e+002 1.432884e+002 3.295569e+000 6.505577e+000 1.361977e+001 3.010028e-001 6.124795e+000 -2.862373e-001
3.125000e+000 9.843750e+001 6.000000e+001 1.450461e+002 -1.444282e+002 1.440907e+002 2.502479e+000 6.696240e+000 1.083095e+001 1.461869e-001 4.761190e+000 -6.997717e-001
4.687500e+000 9.843750e+001 6.000000e+001 1.459731e+002 -1.445299e+002 1.458640e+002 2.384276e-001 6.050995e+000
. . .
Edpiv pE 2013 — help