Pressure drop on the tube
 

hi all
How can i show Pressure drop vs. tube length in CFX-post???

you mean as in a chart form?

Over simplified answer is: run a line through the pipe. Plot pressure on line vs x (or y or z) assuming it is aligned with one of those.

You can do variations on this as you see fit.

create a line with two points (from inlet to outlet)
go to 'charts' and plot the data!