pressure value out of domain!
 

I'm simulating a weir in a channel. I want to read pressure in some specific points. I draw a line with "cut" option then I read pressure at the first point of the line but I noticed that there are some pressure values below this point out of the domain. How is it possible?! what's the problem?

The cut option is giving you a value at every point that curve cuts a control volume boundary face.

I know that but I can also read pressure values by probe tool. how is it possible to exist values for pressure out of domain?!

It is interpolating from the control volume points to the locations you are specifying. The interpolation is not perfect and can result in locally strange results.

alternative is to create a contour on X, Y, Z, or theta on a plane or iso surface. If this gives a contour line where you are interested, create a polyline from this contour line and see if the problem remains.
or create a polyline from a boundary intersection.

thank you all.