Simple utility interpolation method
 

Dear Foamers,

recently, i am working on a simulation. i have generated many models for my simulation. all with same geometry but with different dimension only "x-direction". after the simulation i run sample utility to plot data from the case.

plot line in at the centre of my channel from inlet to outlet. my channel is 30 cells height. so, centre line lie between cells 15 and 16. plot line is chosen to be 20 points for all cases. cases are names are referring to the channel length as 600, 700, 800, 900, and 1000.

I guess that the first point velocity value always is the same and is average value of velocities at cells 15 and 16 (velocity boundary condition is set as non uniform at the entry).

what i got is that value of first point velocity for all cases is similar except one case "900" gives another value. any way the two values are not as i expected "not the average of two cells values".

i was surprised when i changed the end point of plot line for case "900" and sample utility gave the same value of velocity as other cases. the more surprising for me is when i changed the end point of other cases to be 900 i got the value of velocity as of case 900.

which means i got the first point velocity value depending on the end point of the plot line regardless the actual length of the case. and the problem only occurs with one end point "900".

i tried to use plot line filter in paraView with 19 sectors to give me 20 points. and i got a velocity values as i expected "average of two cells centre value".

so my questions are:

1- how sample interpolate values of velocity stored in cell centre to give values of points at plot line?.

2- how plot line filter in paraView is different from sample utility?

3- did i commit any mistakes or misunderstand the function of sample utility?

thanks for your patience and reading, very sorry for long thread.