[samiam1000]

Dear Foamers,

I am trying to figure out how the data-sampling works in OpenFOAM. I am attaching a very simple case.

What I am doing is to compare the point value for the velocity both using the sample function and using paraview (save data).

As far as the sampling is concerned, please refer to the following:
Points:

9
(
(0 1 0)
(0 1 0.5)
(0.5 1 0.5)
(0.5 1 0)
(0 1 1)
(0.5 1 1)
(1 1 0.5)
(1 1 0)
(1 1 1)
)

and velocity vector:

9
(
(2.50406934788e-07 0.0333363500503 2.03689961884e-07)
(2.20364168892e-07 0.0500041590215 3.01401880378e-07)
(4.32465092261e-07 0.100007811468 2.92313951714e-07)
(3.71477651481e-07 0.050004098157 1.5028844484e-07)
(4.34119570677e-08 0.0333358619783 1.98179211954e-07)
(6.09874407803e-08 0.050003713311 1.42025506874e-07)
(2.12100923369e-07 0.0500036524465 -9.08792866413e-09)
(2.4489660052e-07 0.0333357808257 -3.30536876394e-09)
(3.79046306393e-08 0.0333357557697 -8.8118694549e-09)
)

The results from paraview, are here:

"U:0","U:1","U:2","Points:0","Points:1","Points:2"
7.5122e-07,0.10001,6.1107e-07,0,1,0
4.4073e-07,0.10001,6.028e-07,0,1,0.5
4.3247e-07,0.10001,2.9231e-07,0.5,1,0.5
7.4296e-07,0.10001,3.0058e-07,0.5,1,0
1.3024e-07,0.10001,5.9454e-07,0,1,1
1.2197e-07,0.10001,2.8405e-07,0.5,1,1
4.242e-07,0.10001,-1.8176e-08,1,1,0.5
7.3469e-07,0.10001,-9.9161e-09,1,1,0
1.1371e-07,0.10001,-2.6436e-08,1,1,1

Why are the values of the velocity in the 2 cases so different? Am I missing something?

Thanks for help,
Samuele.

[AA29]

Hi Samuelle,

I saw that in your sampleDict file you have turned on interpolation. I am not sure but that might be causing the difference between the sampled values and one obtained from paraView.

-Animesh